Methods and systems for utilizing a unified namespace

ABSTRACT

A method for managing file systems includes receiving, by a unified namespace manager, a first message that indicates a new file system has been created on a first node, performing an update on a top level file system namespace to include a reference to the new file system to generate an updated top level file system namespace, generating, based on the update, a second message that indicates the top level file system namespace has been updated, and sending, to a second node, the second message.

BACKGROUND

Devices and/or components of devices are often capable of performingcertain functionalities that other devices and/or components are notconfigured to perform and/or are not capable of performing. In suchscenarios, it may be desirable to adapt one or more system to enhancethe functionalities of devices and/or components that cannot perform theone or more functionalities.

SUMMARY

In general, in one aspect, the invention relates to a method formanaging file systems. The method includes receiving, by a unifiednamespace manager, a first message that indicates a new file system hasbeen created on a first node, performing an update on a top level filesystem namespace to include a reference to the new file system togenerate an updated top level file system namespace, generating, basedon the update, a second message that indicates the top level file systemnamespace has been updated, and sending, to a second node, the secondmessage.

In general, in one aspect, the invention relates to a non-transitorycomputer readable medium that includes instructions which, when executedby a computer processor, enables the computer processor to perform amethod for managing file systems. The method includes receiving, by aunified namespace manager, a first message that indicates a new filesystem has been created on a first node, performing an update on a toplevel file system namespace to include a reference to the new filesystem to generate an updated top level file system namespace,generating, based on the update, a second message that indicates the toplevel file system namespace has been updated, and sending, to a secondnode, the second message.

In general, in one aspect, the invention relates to a unified namespacemanager that includes a processor, wherein the processor is configuredto receive a first message that indicates a new file system has beencreated on a first node, perform an update on a top level file systemnamespace to include a reference to the new file system to generate anupdated top level file system namespace, generate, based on the update,a second message that indicates the top level file system namespace hasbeen updated, and send, to a second node, the second message.

Other aspects of the invention will be apparent from the followingdescription and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a diagram of a system in accordance with one or moreembodiments of the invention.

FIG. 2 shows a diagram of a node in accordance with one or moreembodiments of the invention.

FIG. 3 shows an example of a node in accordance with one or moreembodiments of the invention.

FIG. 4 shows relationships between various virtual and physical elementsin the system in accordance with one or more embodiments of theinvention.

FIG. 5 shows a flowchart of a method of configuring the system inaccordance with one or more embodiments of the invention.

FIG. 6A shows a flowchart of a method of generating and servicing awrite request in accordance with one or more embodiments of theinvention.

FIG. 6B shows a flowchart of a method of servicing a write request inaccordance with one or more embodiments of the invention.

FIG. 7A shows a flowchart of a method of generating and servicing a readrequest in accordance with one or more embodiments of the invention.

FIG. 7B shows a flowchart of a method of servicing a mapping request inaccordance with one or more embodiments of the invention.

FIG. 8A shows a flowchart of a method of directly reading data inaccordance with one or more embodiments of the invention.

FIG. 8B shows a flowchart of a method of directly writing data inaccordance with one or more embodiments of the invention.

FIG. 9A shows a flowchart of a method of committing data in accordancewith one or more embodiments of the invention.

FIG. 9B shows a flowchart of a method of servicing a sync command inaccordance with one or more embodiments of the invention.

FIG. 10 shows an example in accordance with one or more embodiments ofthe invention.

FIG. 11 shows an example in accordance with one or more embodiments ofthe invention.

FIG. 12 shows an example in accordance with one or more embodiments ofthe invention.

FIG. 13 shows a diagram of a cluster in accordance with one or moreembodiments of the invention.

FIG. 14 shows an example of a two-node system in accordance with one ormore embodiments of the invention.

FIG. 15 shows relationships between various virtual and physicalelements in the system in accordance with one or more embodiments of theinvention.

FIG. 16 shows a flowchart of a method of generating and servicing a readrequest in accordance with one or more embodiments of the invention.

FIG. 17 shows a flowchart of a method of servicing a mapping request inaccordance with one or more embodiments of the invention.

FIG. 18A shows a flowchart of a method of generating a data layoutrequest in accordance with one or more embodiments of the invention.

FIG. 18B shows a flowchart of a method of servicing a data structurerequest in accordance with one or more embodiments of the invention.

FIG. 18C shows a flowchart of a method of servicing a data layoutrequest in accordance with one or more embodiments of the invention.

FIG. 18D shows a flowchart of a method of generating a data request inaccordance with one or more embodiments of the invention.

FIG. 18E shows a flowchart of a method of servicing a data request inaccordance with one or more embodiments of the invention.

FIG. 19A shows a flowchart of a method of committing data in accordancewith one or more embodiments of the invention.

FIG. 19B shows a flowchart of a method of servicing a sync command inaccordance with one or more embodiments of the invention.

FIG. 19C shows a flowchart of a method of servicing a write request inaccordance with one or more embodiments of the invention.

FIG. 20 shows an example in accordance with one or more embodiments ofthe invention.

FIG. 21 shows an example in accordance with one or more embodiments ofthe invention.

FIG. 22 shows a diagram of a cluster, in accordance with one or moreembodiments of the invention.

FIG. 23 shows a diagram of top level file system namespace, inaccordance with one or more embodiments of the invention.

FIG. 24A shows a flowchart of a method of creating a new file system, inaccordance with one or more embodiments of the invention.

FIG. 24B shows a flowchart of a method of updating a top level filesystem namespace, in accordance with one or more embodiments of theinvention.

FIG. 25 shows a flowchart of a method of requesting a top level filesystem namespace, in accordance with one or more embodiments of theinvention.

FIG. 26 shows a flowchart of a method of mounting a file system, inaccordance with one or more embodiments of the invention.

FIG. 27 shows an example, in accordance with one or more embodiments ofthe invention.

FIG. 28 shows an example, in accordance with one or more embodiments ofthe invention.

DETAILED DESCRIPTION

Specific embodiments will now be described with reference to theaccompanying figures. In the following description, numerous details areset forth as examples of the invention. One of ordinary skill in theart, having the benefit of this detailed description, would appreciatethat one or more embodiments of the present invention may be practicedwithout these specific details and that numerous variations ormodifications may be possible without departing from the scope of theinvention. Certain details known to those of ordinary skill in the artmay be omitted to avoid obscuring the description.

In the following description of the figures, any component describedwith regard to a figure, in various embodiments of the invention, may beequivalent to one or more like-named components shown and/or describedwith regard to any other figure. For brevity, descriptions of thesecomponents may not be repeated with regard to each figure. Thus, eachand every embodiment of the components of each figure is incorporated byreference and assumed to be optionally present within every other figurehaving one or more like-named components. Additionally, in accordancewith various embodiments of the invention, any description of anycomponent of a figure is to be interpreted as an optional embodiment,which may be implemented in addition to, in conjunction with, or inplace of the embodiments described with regard to a correspondinglike-named component in any other figure.

Throughout the application, ordinal numbers (e.g., first, second, third,etc.) may be used as an adjective for an element (i.e., any noun in theapplication). The use of ordinal numbers is not to imply or create anyparticular ordering of the elements nor to limit any element to beingonly a single element unless expressly disclosed, such as by the use ofthe terms “before”, “after”, “single”, and other such terminology.Rather, the use of ordinal numbers is to distinguish between theelements. By way of an example, a first element is distinct from asecond element, and the first element may encompass more than oneelement and succeed (or precede) the second element in an ordering ofelements.

As used herein, the term ‘operatively connected’, or ‘operativeconnection’, means that there exists between elements/components/devicesa direct or indirect connection that allows the elements to interactwith one another in some way (e.g., via the exchange of information).For example, the phrase ‘operatively connected’ may refer to any direct(e.g., wired or wireless connection directly between two devices) orindirect (e.g., wired and/or wireless connections between any number ofdevices connecting the operatively connected devices) connection.

In general, embodiments of the invention relate to systems, devices, andmethods for implementing and leveraging persistent memory to improveperformance of data requests. More specifically, embodiments of theinvention relate to a data management service that identifies,intercepts, and redirects requests to appropriate physical devices tooptimize utilization of components of the system. Further, embodimentsof the invention are directed to allowing for direct manipulation ofpersistent memory.

Embodiments of the invention described herein allow for, at least,implementing and intelligently leveraging memory to enhance performance.While the invention has been described with respect to a limited numberof embodiments and examples, those skilled in the art, having benefit ofthis detailed description, would appreciate that other embodiments canbe devised which do not depart from the scope of the invention asdisclosed herein. Accordingly, the scope of the invention should belimited only by the attached claims.

FIG. 1 shows a diagram of a system in accordance with one or moreembodiments of the invention. The system includes one or more client(s)(100), operatively connected to a network (102), which is operativelyconnected to one or more node(s) (104). The components illustrated inFIG. 1 may be connected via any number of operable connections supportedby any combination of wired and/or wireless networks (e.g., network(102)). Each component of the system of FIG. 1 is discussed below.

In one embodiment of the invention, client(s) (100) are configured toissue requests to the node(s) (104) (or to a specific node of thenode(s) (104)), to receive responses, and to generally interact with thevarious components of a node (described below).

In one or more embodiments of the invention, client(s) (100) areimplemented as computing devices. Each computing device may include oneor more processors, memory (e.g., random access memory), and persistentstorage (e.g., disk drives, solid state drives, etc.). The persistentstorage may store computer instructions, (e.g., computer code), thatwhen executed by the processor(s) of the computing device cause thecomputing device to issue one or more requests and to receive one ormore responses. Examples of a computing device include a mobile phone,tablet computer, laptop computer, desktop computer, server, distributedcomputing system, or cloud resource.

In one or more embodiments of the invention, the client(s) (120) isimplemented as a logical device. The logical device may utilize thecomputing resources of any number of computing devices and therebyprovide the functionality of the client(s) (100) described throughoutthis application.

In one or more embodiments of the invention, client(s) (100) may requestdata and/or send data to the node(s) (104). Further, in one or moreembodiments, client(s) (100) may initiate an application to execute onone or more node(s) (104) such the application may, itself, gather,transmit, and/or otherwise manipulate data on the node (e.g., node(s)(104)), remote to the client(s). In one or more embodiments, one or moreclient(s) (100) may share access to the same one or more node(s) (104)and may similarly share any data located on those node(s) (104).

In one or more embodiments of the invention, network (102) of the systemis a collection of connected network devices that allow for thecommunication of data from one network device to other network devices,or the sharing of resources among network devices. Examples of a network(e.g., network (102)) include, but are not limited to, a local areanetwork (LAN), a wide area network (WAN) (e.g., the Internet), a mobilenetwork, or any other type of network that allows for the communicationof data and sharing of resources among network devices and/or devices(e.g., clients (100), node(s) (104)) operatively connected to thenetwork (102). In one embodiment of the invention, the client(s) (100)are operatively connected to the node(s) (104) via a network (e.g.,network (102)).

Various embodiments of the node(s) (104) are provided in FIG. 2 and FIG.3 below.

While FIG. 1 shows a specific configuration of a system, otherconfigurations may be used without departing from the scope of thedisclosure. For example, although the client(s) (100) and node(s) (104)are shown to be operatively connected through network (102), client(s)(100) and node(s) (104) may be directly connected, without anintervening network (e.g., network (102)). Further, the functioning ofthe client(s) (100) and the node(s) (104) is not dependent upon thefunctioning and/or existence of the other device(s) (e.g., node(s) (104)and client(s) (100), respectively). Rather, the client(s) (100) and thenode(s) (104) may function independently and perform operations locallythat do not require communication with other devices. Accordingly,embodiments disclosed herein should not be limited to the configurationof devices and/or components shown in FIG. 1.

FIG. 2 shows a diagram of a node (200) in accordance with one or moreembodiments of the invention. In one embodiment of the invention, node(200) includes one or more application container(s) (e.g., applicationcontainer A (202), application container B (204)), a file systemcontainer (206), an operating system (OS) (208), and a hardware layer(210). Each of these components is described below. In one or moreembodiments of the invention, the node (200) is configured to performall, or a portion, of the functionality described in FIGS. 5-11.

In one or more embodiments of the invention, an application container(202, 204) is software executing on the node. In one embodiment of theinvention, an application container (202, 204) may be an independentsoftware instance that executes within a larger container managementsoftware instance (not shown) (e.g., Docker®, Kubernetes®). In oneembodiment, where the application container (202, 204) is executing asan isolated software instance, the application container (202, 204) mayestablish a semi-isolated virtual environment, inside the container, inwhich to execute one or more applications (e.g., applications (212, 214,216, 218), described below). In one embodiment of the invention, anapplication container (202, 204) may be executing in “user space” (e.g.,a layer of the software that utilizes low-level system components forthe execution of applications) of the operating system (OS) (208) of thenode (200).

In one or more embodiments of the invention, an application container(202, 204) includes one or more applications (e.g., application C (212),application D (214), application E (216), application F (218)). In oneembodiment of the invention, an application (212, 214, 216, 218) issoftware executing within the application container (e.g., 202, 204),that may include instructions which, when executed by a processor(s)(234), initiate the performance of one or more operations of componentsof the hardware layer (210). Although applications (212, 214, 216, 218)are shown executing within application containers (202, 204) of FIG. 2,one or more applications (e.g., 212, 214, 216, 218) may execute outsideof an application container (e.g., 212, 214, 216, 218). That is, in oneor more embodiments, one or more applications (e.g., 212, 214, 216, 218)may execute in a non-isolated instance, at the same level as theapplication container (202, 204) or file system container (206).

In one or more embodiments of the invention, each application (212, 214,216, 218) includes a virtual address space (e.g., virtual address space(220), virtual address space (222), virtual address space (224), virtualaddress space (226)). In one embodiment of the invention, a virtualaddress space (220, 222, 224, 226) is a simulated range of addresses(e.g., identifiable locations) that mimics the physical locations of oneor more components of the hardware layer (210). In one embodiment, anapplication (212, 214, 216, 218) is not configured to identify thephysical addresses of one or more components of the hardware layer(210); rather, the application (212, 214, 216, 218) relies on othercomponents of the node (200) to translate one or more virtual addressesof the virtual address space (e.g., 220, 222, 224, 226) to one or morephysical addresses of one or more components of the hardware layer(210). Accordingly, in one or more embodiments of the invention, anapplication may utilize a virtual address space (220, 222, 224, 226) toread, write, and/or otherwise manipulate data, without being configuredto directly identify the physical address of that data within thecomponents of the hardware layer (210).

Additionally, in one or more embodiments of the invention, anapplication may coordinate with other components of the node (200) toestablish a mapping between a virtual address space (e.g., 220, 222,224, 226) and underlying physical components of the hardware layer(210). In one embodiment, if a mapping is established, an application'suse of the virtual address space (e.g., 220, 222, 224, 226) enables theapplication to directly manipulate data of those physical components,without relying on other components of the node (200) to repeatedlyupdate mappings between the virtual address space (e.g., 220, 222, 224,226) and the physical addresses of one or more components of thehardware layer (210).

In one or more embodiments of the invention, a file system container(206) is software executing on the node (200). In one or moreembodiments of the invention, a file system container (206) may be anindependent software instance that executes within a larger containermanagement software instance (not shown) (e.g., Docker®, Kubernetes®,etc.). In one embodiment, where the file system container (206) isexecuting as an isolated software instance, the file system container(206) may establish a semi-isolated virtual environment, inside thecontainer, in which to execute an application (e.g., space manager(228), described below). In one embodiment of the invention, a filesystem container (206) may be executing in “user space” (e.g., a layerof the software that utilizes low-level system components for theexecution of applications) of the OS (208).

In one embodiment of the invention, the file system container (206)includes a space manager (228). In one embodiment, a space manager (228)is software executing within the file system container (206), that mayinclude instructions which, when executed, initiate operations of one ormore components in the hardware layer (210).

In one or more embodiments of the invention, a space manager (228) mayinclude functionality to generate one or more virtual-to-physicaladdress mappings by translating a virtual address of a virtual addressspace (220, 222, 224, 226) to a physical address of a component in thehardware layer (210). Further, in one embodiment of the invention, thespace manager may further be configured to communicate one or morevirtual-to-physical address mappings to one or more components of thehardware layer (210) (e.g., memory management unit (240)). In oneembodiments of the invention, the space manager (228) tracks andmaintains virtual-to-physical address mappings through an abstractionlayer(s) of virtual spaces that form a hierarchy of mappings totranslate a virtual address to a physical address. In one or moreembodiments of the invention, the space manager (228) is configured tomaintain and utilize a hierarchy of addresses (via a sparse virtualspace, one or more memory pool(s), and one or more persistent storagepool(s)) a described in FIG. 4. Additionally, in one or more embodimentsof the invention, a space manager is configured to initiate the copyingof data from one storage medium to another based on a determination thata storage device may be incapable of servicing an application request.

In one or more embodiments of the invention, an OS (208) is softwareexecuting on the node (200). In one embodiment of the invention, an OS(208) coordinates operations between software executing in “user space”(e.g., containers (202, 204, 206), applications (212, 214, 216, 218))and one or more components of the hardware layer (210) to facilitate theproper use of those hardware layer (210) components. In one or moreembodiments of the invention, the OS (208) includes a kernel module(230). In one embodiment of the invention, the kernel module (208) issoftware executing in the OS (208) that monitors data (which may includeread and write requests) traversing the OS (208) and may intercept,modify, and/or otherwise alter that data based on one or moreconditions. In one embodiment of the invention, the kernel module (230)is capable of redirecting data received by the OS (208) by interceptingand modifying that data to specify a recipient different than normallyspecified by the OS (208).

In one or more embodiments of the invention, the hardware layer (210) isa collection of physical components configured to perform the operationsof the node (200) and/or otherwise execute the software of the node(200) (e.g., those of the containers (202, 204, 206), applications (212,214, 216, 218).

In one embodiment of the invention, the hardware layer (210) includesone or more communication interface(s) (232). In one embodiment of theinvention, a communication interface (232) is a hardware component thatprovides capabilities to interface the node (200) with one or moredevices (e.g., a client, another node, a network of devices) and allowfor the transmission and receipt of data with those device(s). Acommunication interface (232) may communicate via any suitable form ofwired interface (e.g., Ethernet, fiber optic, serial communication etc.)and/or wireless interface and utilize one or more protocols for thetransmission and receipt of data (e.g., Transmission Control Protocol(TCP)/Internet Protocol (IP), Remote Direct Memory Access, IEEE 801.11,etc.).

In one embodiment of the invention, the hardware layer (210) includesone or more processor(s) (234). In one embodiment of the invention, aprocessor (234) may be an integrated circuit for processing instructions(e.g., those of the containers (202, 204, 206), applications (212, 214,216, 218) and/or those received via a communication interface (232)). Inone embodiment of the invention, processor(s) (234) may be one or moreprocessor cores or processor micro-cores. Further, in one or moreembodiments of the invention, one or more processor(s) (234) may includecache (as described in FIG. 3 below).

In one or more embodiments of the invention, the hardware layer (210)includes persistent storage (236). In one embodiment of the invention,persistent storage (236) may be one or more hardware devices capable ofstoring digital information (e.g., data) in a non-transitory medium.Further, in one embodiment of the invention, when accessing persistentstorage (236), other components of node (200) are capable of onlyreading and writing data in fixed-length data segments (e.g., “blocks”)that are larger than the smallest units of data normally accessible(e.g., “bytes”).

Specifically, in one or more embodiments of the invention, when data isread from persistent storage (236), all blocks that include therequested bytes of data (some of which may include other, non-requestedbytes of data) must be copied to other byte-accessible storage (e.g.,memory). Then, only after the data is located in the other medium, maythe requested data be manipulated at “byte-level” before beingrecompiled into blocks and copied back to the persistent storage (236).

Accordingly, as used herein, “persistent storage”, “persistent storagedevice”, “block storage”, “block device”, and “block storage device”refer to hardware storage devices that are capable of being accessedonly at a “block-level” regardless of whether that device is volatile,non-volatile, persistent, non-persistent, sequential access, randomaccess, solid-state, or disk based. Further, as used herein, the term“block semantics” refers to the methods and commands software employs toaccess persistent storage (236).

Examples of “persistent storage” (236) include, but are not limited to,certain integrated circuit storage devices (e.g., solid-state drive(SSD), Non-Volatile Memory Express (NVMe) etc.), magnetic storage (e.g.,hard disk drive (HDD), floppy disk, tape, diskette, etc.), or opticalmedia (e.g., compact disc (CD), digital versatile disc (DVD), etc.).

In one or more embodiments of the invention, the hardware layer (210)includes memory (238). In one embodiment of the invention, memory (238),similar to persistent storage (236), may be one or more hardware devicescapable of storing digital information (e.g., data) in a non-transitorymedium. However, unlike persistent storage (236), in one or moreembodiments of the invention, when accessing memory (238), othercomponents of node (200) are capable of reading and writing data at thesmallest units of data normally accessible (e.g., “bytes”).

Specifically, in one or more embodiments of the invention, memory (238)may include a unique physical address for each byte stored thereon,thereby enabling software (e.g., applications (212, 214, 216, 218),containers (202, 204, 206)) to access and manipulate data stored inmemory (238) by directing commands to a physical address of memory (238)that is associated with a byte of data (e.g., via a virtual-to-physicaladdress mapping). Accordingly, in one or more embodiments of theinvention, software is able to perform direct, “byte-level” manipulationof data stored in memory (unlike persistent storage data, which mustfirst copy “blocks” of data to another, intermediary storage mediumsprior to reading and/or manipulating data located thereon).

Accordingly, as used herein, “memory”, “memory device”, “memory storage,“memory storage device”, and “byte storage device” refer to hardwarestorage devices that are capable of being accessed and/or manipulated ata “byte-level” regardless of whether that device is volatile,non-volatile, persistent, non-persistent, sequential access, randomaccess, solid-state, or disk based. As used herein, the terms “bytesemantics” and “memory semantics” refer to the methods and commandssoftware employs to access memory devices (238).

Examples of memory (238) devices include, but are not limited to,certain integrated circuit storage (e.g., flash memory, random accessmemory (RAM), dynamic RAM (DRAM), resistive RAM (ReRAM), etc.). Further,hybrid devices that contain multiple forms of storage (e.g., anon-volatile dual in-line memory module (NVDIMM)) may be considered“memory” if the hybrid device component that interacts with the node iscapable of being accessed and/or manipulated at a “byte-level”. Forexample, a “persistent memory” (PMem) module that includes, for example,a combination of DRAM, flash memory, and a capacitor (for persistingDRAM data to flash memory in the event of power loss) is considered“memory” as the DRAM component (the component of the module accessibleby the memory management unit) is capable of being accessed and/ormanipulated at a “byte-level”.

In one embodiment of the invention, the hardware layer (210) includes amemory management unit (MMU) (240). In one or more embodiments of theinvention, an MMU (240) is hardware configured to translate virtualaddresses (e.g., those of a virtual address space (220, 222, 224, 226))to physical addresses (e.g., those of memory (238)). In one embodimentof the invention, an MMU (240) is operatively connected to memory (238)and is the sole path to access any memory device (e.g., memory (238)) asall commands and data destined for memory (238) must first traverse theMMU (240) prior to accessing memory (238). In one or more embodiments ofthe invention, an MMU (240) may be configured to handle memoryprotection (allowing only certain applications to access memory) andprovide cache control and bus arbitration. Further, in one or moreembodiments of the invention, an MMU (240) may include a translationlookaside buffer (as described in FIG. 3 below).

While FIG. 2 shows a specific configuration of a node, otherconfigurations may be used without departing from the scope of thedisclosure. Accordingly, embodiments disclosed herein should not belimited to the configuration of devices and/or components shown in FIG.2.

FIG. 3 shows an example of one embodiment of a node (300). In oneembodiment of the invention, node (300) includes an applicationcontainer (302) with application (312) and virtual address space (320),a file system container (306) with space manager (328), an OS (308) withkernel module (330), and a hardware layer (310) with communicationinterface (332), processor (334) with cache (335), MMU (340) with atranslation lookaside buffer (TLB) (341), persistent storage (336), andmemory (338). Similarly named parts shown in FIG. 3 have all of the sameproperties and functionalities as described above in FIG. 2.Accordingly, only additional properties and functionalities will bedescribed below.

In one or more embodiments of the invention, processor (334) includescache (335). In one embodiment of the invention, cache (335) may be oneor more hardware devices capable of storing digital information (e.g.,data) in a non-transitory medium. Cache (335) may be used internally bythe processor (334) to perform operations on data, as requested by oneor more software instances (e.g., application container (302),application (312), file system container (306), space manager (328), OS(308), etc.) or hardware layer components (e.g., communication interface(332), MMU (340), TLB (341), etc.).

In one or more embodiments of the invention, cache (335) is a limitedresource (e.g., little total space) and may therefore reach a maximumcapacity more quickly than other devices of the hardware layer (e.g.,persistent storage (336) and memory (338)). However, although limited intotal capacity, cache may be significantly faster at performingoperations (e.g., reading, writing) than other devices of the hardwarelayer (e.g., persistent storage (336) and memory (338)). In oneembodiment of the invention, data may only be located in cachetemporarily, prior to being copied to memory (338) and/or persistentstorage (336). Further data, located in cache, may be considered“uncommitted” or “dirty” until copied to memory (338) and/or persistentstorage (336).

In one or more embodiments of the invention, MMU (340) includes TLB(341). In one embodiment of the invention, TLB (341) may be one or morehardware devices capable of storing digital information (e.g., data) ina non-transitory medium. Specifically, in one embodiment of theinvention, the TLB (341) stores one or more virtual-to-physical addressmappings which the MMU may access.

In one or more embodiments of the invention, although memory (338) mayuse a series of physical addresses to locate data, application (312)uses a series of virtual addresses (e.g., those of virtual address space(320)) to reference data. Accordingly, the TLB (341) provides the MMU(340) a translation table that includes one or more virtual-to-physicaladdress mappings to identify the physical address of memory (338)associated with a virtual address (as specified by an applicationrequest). Although shown as a component of MMU (340), the TLB (341) maybe located outside of the MMU (340) and inside the hardware layer (310)generally, or as part of processor (334).

In the example shown here, persistent storage (336) is shown to includeone or more NVMe devices and one or more HDD devices. Similarly, in theexample shown here, memory (338) is shown to include a one or more DRAMdevices and one or more PMem devices. These specific instances ofpersistent storage devices and memory devices in FIG. 3 are shown forillustrative purposes only. One of ordinary skill in the art, having thebenefit of this detailed description, would appreciate that persistentstorage (336) and memory (338) may be comprised of any number ofappropriate devices.

While FIG. 3 shows a specific example of a node, other configurationsmay be used without departing from the scope of the disclosure.Accordingly, embodiments disclosed herein should not be limited to theconfiguration of devices and/or components shown in FIG. 3.

FIG. 4 shows a diagram of a virtual-to-physical segment hierarchy inaccordance with one or more embodiments of the invention. In oneembodiment of the invention, the virtual-to-physical segment hierarchyincludes a virtual address space (420), a sparse virtual space (400),one or more memory pool(s) (402), one or more persistent storage pool(s)(404), memory (438), and persistent storage (436). Each of thesecomponents is described below.

In one or more embodiments of the invention, virtual address space (420)has all of the same properties and functionalities as the virtualaddress space(s) described above in FIG. 1. Additionally, in oneembodiment of the invention, a virtual address space (e.g., virtualaddress space (420)) may include one or more virtual address spacesegment(s) (e.g., virtual address space segment (406)). In one or moreembodiments of the invention, a virtual address space segment (406) maycorrespond to some other smaller portion of the virtual address space(420) (e.g., a subset of virtual addresses). In one embodiment of theinvention, virtual address space segment (406) may be associated with asingle virtual address (as described in FIG. 1). In one or moreembodiments of the invention, a virtual address space address segment(406) is mapped to a sparse virtual space segment (408) (describedbelow). In one embodiment of the invention, every virtual address spacesegment (e.g., virtual address space segment (404)) is individually anduniquely mapped to a unique sparse virtual space segment (e.g., sparsevirtual space segment (408)).

In one or more embodiments of the invention, sparse virtual space (400)is a sparse, virtual data structure that provides a comprehensive layoutand mapping of data managed by the file system container of the node. Inone embodiment of the invention, the sparse virtual space (400) spansthe entire virtual-to-physical segment hierarchy, such that everyadjacent layer in in the virtual-to-physical segment hierarchy maps tothe sparse virtual space (400). That is, while there may be multiplevirtual address space(s) (e.g., virtual address space (420), others notshown) and there may be multiple pool(s) for storage (e.g., memorypool(s) (402), persistent storage pool(s) (404)), there is only onesparse virtual space (400).

Further, as the sparse virtual space (400) may need to be continuallyupdated to allow for new internal associations with adjacent layers, thesparse virtual space (400) may be initially allocated substantiallysparse enough to be able to handle new associations without having toallocate additional space outside of that initially reserved.Accordingly, for example, the sparse virtual space may be allocated withseveral petabytes of sparse space, with the intention being that thephysical memory and persistent storage (associated with the sparsevirtual space) will not exceed several petabytes of physical storagespace.

In one or more embodiments of the invention, the sparse virtual space(400) may include one or more sparse virtual space segment(s) (e.g.,sparse virtual space segment (408)). In one embodiment of the invention,a sparse virtual space segment (408) is a smaller virtual sub-region ofthe sparse virtual space (400) that is uniquely associated with somedata. In one or more embodiments of the invention, a sparse virtualspace segment (408) may provide the logical volume and logical volumeoffset for data (physically located in the persistent storage and/ormemory of the node).

In one or more embodiments of the invention, each sparse virtual spacesegment (e.g., sparse virtual space segment (408)) is uniquelyassociated with a unique memory pool segment (410) or a uniquepersistent storage pool segment (412), as explained below.

In one or more embodiments of the invention, each sparse virtual spacesegment (408) may be uniformly sized throughout the sparse virtual space(400). In one or more embodiments of the invention, each sparse virtualspace segment (408) may be equal to the largest memory pool segment(410) or persistent storage pool segment (412) associated with thesparse virtual space (e.g., the largest block of a persistent storagedevice). Alternatively, in one or more embodiments of the invention,each sparse virtual space segment (408) may be allocated to besufficiently larger than any current and future individual memory poolsegment (410) and/or persistent storage pool segment (412) (e.g., largerthan a persistent storage block).

In one or more embodiments of the invention, memory pool(s) (402) arevirtual data spaces that identify physical regions of a portion of, one,or several memory devices (e.g., memory (438)) of the hardware layer.Memory pool(s) (402) may identify physical regions of memory bymaintaining a virtual mapping to the physical addresses of data thatcomprise those memory devices (e.g., memory (438)).

In one or more embodiments of the invention, several memory pools (402)may concurrently exist, each of which is independently mapped to partof, one, or several memory devices (e.g., memory (438)). Alternatively,in one embodiment of the invention, there may only be a single memorypool (402) associated with the physical regions of data of all memorydevices (e.g., memory (438)) in a node.

In one embodiment of the invention, a single memory pool (of memorypool(s) (402)) may be uniquely associated with a single memory device.Accordingly, a single memory pool may provide a one-to-one virtualemulation of a single memory device of the hardware layer.Alternatively, in one or more embodiments of the invention, a singlememory pool may be associated with multiple memory devices, each sharingsome characteristic. For example, there may be a single memory pool fortwo or more DRAM devices and a second memory pool for two or more PMemdevices. One of ordinary skill in the art, having the benefit of thisdetailed description, would appreciate that memory pool(s) (402) may beorganized by any suitable characteristic of the underlying memory (e.g.,based on individual size, collective size, type, speed, etc.).

In one or more embodiments of the invention, memory pool(s) (402)include one or more memory pool segment(s) (e.g., memory pool segment(410)). In one embodiment of the invention, a memory pool segment (410)is a smaller sub-region of a memory pool (402) that is uniquelyassociated with some data located in memory (438). Further, one or morememory pool segment(s) (410) may be uniquely associated with one or moreunique regions of a memory device (e.g., memory segment (414)). Forexample, memory pool segment (410) may be associated with a physicaladdress range on a memory device (e.g., memory (438)) that correspondsto the physical location of a single byte of data (as explained below).

In one or more embodiments of the invention, memory (438) has all of thesame properties and functionalities as the memory described in FIG. 1above. Additionally, as disclosed in FIG. 4, memory (438) may includeone or more memory segment(s) (e.g., memory segment (414)) that dividememory (438) in smaller sub-regions. In one or more embodiments of theinvention, a memory segment (414) is a unique physical region of thememory (438) that stores data and is accessible using a physicaladdress.

In one or more embodiments of the invention, as shown in FIG. 4, two ormore contiguous memory pool segments (410) are associated with two ormore contiguous memory segments (414), respectively. Accordingly, theremay be a sequential mapping between memory (438) and a memory pool (402)such that by referencing a sequence of memory pool segments (e.g., “1”,“2”, “3” of memory pool(s) (402)), a corresponding sequence of memorysegments (e.g., “I”, “II”, “III” of memory (438)) will be accessed.Further, when a direct mapping between a memory pool (402) and memory(438) is maintained, the memory pool, alone, provides an accurate,direct, and sequential representation of the underlying memory (e.g.,total space, data location, available space, etc.). Alternatively, inone embodiment of the invention, a series of memory pool segment(s)(410) are not consecutively associated with a series of memorysegment(s) (414) (not shown).

In one or more embodiments of the invention, persistent storage pool(s)(404) are virtual data spaces that identify regions of a portion of,one, or several persistent storage devices (e.g., persistent storage(436)) of the hardware layer. Persistent storage pool(s) (404) mayidentify physical regions of persistent storage by maintaining a virtualmapping to the physical location of data that comprise those persistentstorage devices (e.g., persistent storage (436)).

In one or more embodiments of the invention, several persistent storagepools (404) may concurrently exist, each of which is independentlymapped to part of, one, or several persistent storage devices (e.g.,persistent storage (436)). Alternatively, in one embodiment of theinvention, there may only be a single persistent storage pool (404)associated with the physical locations of data on all persistent storagedevices (e.g., persistent storage (438)) in a node.

In one embodiment of the invention, a single persistent storage pool (ofpersistent storage pool(s) (404)) may be uniquely associated with asingle persistent storage device. Accordingly, a single persistentstorage pool may provide a one-to-one virtual emulation of a singlepersistent storage device of the hardware layer. Alternatively, in oneor more embodiments of the invention, a single persistent storage poolmay be associated with multiple persistent storage devices, each sharingsome characteristic. For example, there may be a first persistentstorage pool for two or more NVMe devices and a second persistentstorage pool for two or more SSD devices. One of ordinary skill in theart, having the benefit of this detailed description, would appreciatethat persistent storage pool(s) (404) may be organized by any suitablecharacteristic of the underlying persistent storage (e.g., based onindividual size, collective size, type, speed, etc.).

In one or more embodiments of the invention, persistent storage pool(s)(404) include one or more persistent storage pool segment(s) (e.g.,persistent storage pool segment (412)). In one embodiment of theinvention, a persistent storage pool segment (412) is a smallersub-region of a persistent storage pool (404) that is uniquelyassociated with some data located in persistent storage (436). Further,one or more persistent storage pool segment(s) (412) may be uniquelyassociated with one or more unique regions of a persistent storagedevice (e.g., persistent storage segment (416)).

In one or more embodiments of the invention, persistent storage (436)has all of the same properties and functionalities as the persistentstorage described in FIG. 1 above. Additionally, as disclosed in FIG. 4,persistent storage (436) may include one or more persistent storagesegment(s) (e.g., persistent storage segment (416)) that dividepersistent storage (436) in smaller sub-regions. In one or moreembodiments of the invention, a persistent storage segment (416) is aunique physical region of persistent storage (436) that stores data andis accessible using a physical address.

In one or more embodiments of the invention, as shown in FIG. 4, two ormore contiguous persistent storage pool segments (412) are notassociated with two or more contiguous persistent storage segments(416). Accordingly, there may be a non-sequential mapping betweenpersistent storage (436) and a persistent storage pool (404) such thatby referencing a non-sequential series of persistent storage poolsegments (e.g., “α”, “γ”, of persistent storage pool(s) (404)), acorresponding sequential or non-sequential series of persistent storagesegments (e.g., “ii”, “iii” of persistent storage (436)) will beaccessed. Alternatively, in one embodiment of the invention, like memorypool(s) (402) and memory (438), there may be a corresponding sequentialassociation of segments between the persistent storage pool segments(412) and persistent storage segments (416) (not shown).

Accordingly, in one embodiment of the invention, the virtual-to-physicalsegment hierarchy of FIG. 4 provides a mapping from a virtual addressspace segment (406) of an application to a physical location of thehardware (memory segment (414) or persistent storage segment (416)).

As an example, virtual address space (420) may correspond to a singlefile being accessed by the application where each virtual address spacesegment (“a”, “b”, “c”, and “d”) represent four bytes of that file. Inorder for the application to access those four bytes, the space managerlocates, in the sparse virtual space, the unique sparse virtual spacesegments that are associated with those four bytes (“D”, “F”, “B”, and“H”, respectively). In turn, two of those sparse virtual space segments(“B” and “F”) are mapped to two memory pool segments (“2” and “3”,respectively); while the other two sparse virtual space segments (“D”and “H”) are mapped to two persistent pool segments (“α” and “γ”,respectively). As the memory pool (402) maintains a one-to-onesequential mapping to memory (438), the two memory pool segments, “2”and “3”, directly correspond to memory segments “II” and “III”. Forpersistent storage pool (404), however, a sequential mapping topersistent storage (436) is not maintained, and the two persistent poolsegments, “α” and “γ”, are associated with persistent storage segments“ii” and “iii”, respectively. Accordingly, the original segments of data(“a”, “b”, “c”, and “d”) may be translated to the physical locations ofeach segment (“ii”, “III”, “II”, and “ii”, respectively) using thevirtual-to-physical segment hierarchy.

While FIG. 4 shows a specific configuration of a virtual-to-physicalsegment hierarchy, other configurations may be used without departingfrom the scope of the disclosure. For instance, as discussed above,there may be many virtual address spaces of several applications thatmay access the sparse virtual space to identify the physical location ofdata. Further, there can be any number of memory pools and/or persistentstorage pools mapping into the sparse virtual space. Similarly, thememory pools and persistent storage pools may be mapped into any numberof memory and persistent storage devices, respectively. Accordingly,embodiments disclosed herein should not be limited to the configurationof devices and/or components shown in FIG. 4.

FIG. 5 shows a flowchart of a method of creating a memory pool and asparse virtual space, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 5 may beperformed by the space manager. Another component of the system mayperform this method without departing from the invention. While thevarious steps in this flowchart are presented and describedsequentially, one of ordinary skill in the relevant art will appreciatethat some or all of the steps may be executed in different orders, maybe combined or omitted, and some or all steps may be executed inparallel.

In Step 500, a space manager identifies one or more memory devices towhich the node has access. In one or more embodiments of the invention,the selection of memory devices may be based on connectivity (i.e., ifan operative connection to the memory devices exists), permissions toaccess the memory device, physical location (e.g., located within thenode, or accessible through a communication interface), and/or othermanagement roles (e.g., file system ownership). Further, some portion ofa single memory device may be available to a space manager, whileanother portion of that same memory device will be inaccessible based onone or more of the aforementioned characteristics.

In one or more embodiments of the invention, a space manager will becaused to identify all memory devices to which the node has access (Step500) based on one or more conditions including, for example, the nodebeing initially configured, a change in the hardware being detected,user instruction, and/or other any other event that would cause thespace manager to need to establish (or otherwise update) a sparsevirtual space and memory pools.

In Step 502, the space manager allocates one or more memory poolscorresponding to the one or more memory devices identified in Step 500.Specifically, as discussed above with respect to FIG. 4, memory poolsmay be created and/or organized based on any suitable characteristic ofthe underlying memory (e.g., individual size, collective size, type,speed, etc.). For example, if two DRAM devices and one PMem areidentified in Step 500, the space manager may create two memory pools,one memory pool for both DRAM devices, and one memory pool for the PMemdevice.

Further, in one embodiment of the invention, the memory pool(s) createdby the space manager are created to correspond to the size of theunderlying memory. For example, if the first DRAM device is 1,000 Mb,the second DRAM device is 1,500 Mb, and the PMem device is 2,000 Mb, thefirst memory pool (associated with the DRAM) will need to be at least2,500 Mb of virtual space whereas the second memory pool will need to beat least 2,000 Mb of virtual space.

Continuing with the example, if a first memory pool corresponds to twoDRAM devices, the space manager may associate a first portion of thememory pool to the first DRAM device and a second portion of the memorypool to the second DRAM device. Then, assuming the same sizes describedabove, the first memory pool (associated with the DRAM devices) isdivided into two portions, 1,000 Mb for the first portion, 1,500 Mb forthe second portion. Further, as the second memory pool is onlyassociated with a single PMem device, there is no need to allocate adevice-level portion in the second memory pool.

In Step 504, the space manager partitions the memory pool(s) into anappropriate number of memory pool segments corresponding to the memorydevices identified in Step 500. The size of each of the memory poolsegments may be determined by the space manager and/or based on theunderlying characteristics of the memory devices.

In one or more embodiments of the invention, each memory pool is dividedinto the number of segments equal to the number of bytes accessible onthat memory device (e.g., memory segments). Continuing with the exampleabove, the first region of the first memory pool (associated with the1,000 Mb DRAM device) is partitioned into 1,000 segments. The secondregion of the first memory pool (associated with the 1,500 Mb DRAMdevice) is partitioned into 1,500 segments. And, finally, the secondmemory pool (associated with the 2,000 Mb PMem device) is partitionedinto 2,000 segments, corresponding to the 2,000 Mb of that PMem device.

In one or more embodiments of the invention, once each memory pool ispartitioned into memory pool segments, each memory pool segment isassociated with a corresponding memory segment. Thus, for example, thefirst memory segment of the first DRAM device is associated with thefirst memory pool segment of the first memory pool associated with DRAMdevice. Then, for each sequential addressable region of the memorydevice, the same association may be established with correspondingmemory pool segment.

In Step 506, each memory pool segment is associated with a unique sparsevirtual space segment. In one or more embodiments of the invention, inthe event that the sparse virtual space does not yet exist, the spacemanager allocates a sufficiently large region of virtual space to allowfor associations to all existing and future memory devices. As describedabove for FIG. 4, the sparse virtual space may be allocated with severalpetabytes of sparse space, with the intention being that the physicalmemory and persistent storage (associated with the sparse virtual space)will not exceed several petabytes of physical storage space.

In one or more embodiments of the invention, after the creation of thesparse virtual space, the space manager divides the entire sparsevirtual space into uniformly sized segments. As described above for FIG.4, in one or more embodiments of the invention, each sparse virtualspace segment may be allocated to be sufficiently larger than anycurrent and future individual memory pool segment and/or persistentstorage pool segment (e.g., larger than a persistent storage block).

In one or more embodiments of the invention, once the sparse virtualspace is partitioned into a very large number of sparse virtual spacesegments, each memory pool segment (created in Step 504) is associatedwith one of the sparse virtual space segments. In one embodiment of theinvention, the sparse virtual space segments, associated with the memorypool segments, are scattered throughout the sparse virtual space with noparticular ordering. Alternatively, in one embodiment of the invention,the sparse virtual space segments associated with memory segments aregrouped consecutively, or in multiple consecutive sequences throughoutthe sparse virtual space.

Continuing with the example above, the 3,500 memory pool segmentscreated across the two memory pools would then be associated with 3, 500sparse virtual space segments. In one embodiment of the invention, thesparse virtual space segments associated with the memory pool segmentsmay be spread throughout the sparse virtual space, without any forcedorder or general organization.

Alternatively, in one or more embodiments of the invention, the spacemanager will not, initially, associate any sparse virtual space segmentswith the memory pool segments. Instead, for example, if the memorydevices contain no data, the space manager may wait until a writerequest is received before associating one or more sparse virtual spacesegments with one or more memory pool segments.

Further, while Steps 500-506 only explain the process in relation tomemory and memory devices, this same process may also apply topersistent storage, albeit modified, where necessary, to conform withthe differences between memory and persistent storage, as discussed inFIGS. 2 and 4.

FIG. 6A shows a flowchart of a method for writing new data to memory ofthe node, in accordance with one or more embodiments of the invention.All or a portion of the method shown in FIG. 6A may be performed by oneor more components of the node. While the various steps in thisflowchart are presented and described sequentially, one of ordinaryskill in the relevant art will appreciate that some or all of the stepsmay be executed in different orders, may be combined or omitted, andsome or all steps may be executed in parallel.

In Step 600, an application issues a write request to store new data inthe virtual address space of that application. In one or moreembodiments of the invention, the write request specifies the virtualaddress space segment (e.g., virtual address) and the data to bewritten. Further, in one embodiment of the invention, as the data isnew, there is no known physical location to store the data wheninitially generated, and therefore a location must be newly identified.

In one or more embodiments of the invention, as described in FIG. 1above, the application may be executing within an application containerthat has the ability to access the OS of the node. Thus, when anapplication, isolated in an application container, issues a request toan internal virtual address space, the application container must handlethat command before interacting with the OS.

In Step 602, the application container, to which the applicationbelongs, forwards the write request to the OS. In one or moreembodiments of the invention, although the application issued the writerequest to the virtual address space of the application, such internalrequests ultimately trigger external commands to the underlying OS sothat the request to the virtual address space may be reflected in thehardware devices of the node.

In one or more embodiments of the invention, the application containerforwards the request, unaltered to the OS of the node. Alternatively, inone embodiment of the invention, the application container may modifythe request prior to forwarding, for example, by translating the virtualaddress specified by the application to another virtual address (in theevent of a known conflict) and/or otherwise modify the request toconform with the operation of the node.

In Step 604, the hardware layer of the node issues of page fault to theOS. In one or more embodiments of the invention, a page fault is anexception handling process of the OS caused by one or more components ofthe hardware layer receiving an invalid request.

In one embodiment of the invention, a page fault is issued by aprocessor when an invalid reference is provided to an MMU. Specifically,when a request to access or modify memory is sent to the MMU, using avirtual address, the MMU may perform a lookup in the TLB to find aphysical address associated with the provided virtual address (e.g., avirtual-to-physical address mapping). However, if the TLB does notprovide a physical address associated with the virtual address (e.g.,due to the TLB lacking the appropriate virtual-to-physical addressmapping), the MMU will be unable to perform the requested operation.Accordingly, the MMU informs the processor that the request cannot beserviced, and in turn, the processor issues a page fault back to the OSinforming that the request could not be serviced.

In one or more embodiments of the invention, the page fault specifiesthe original write request (i.e., the data to be written and the virtualaddress) and the reason for the page fault (that the MMU could notlocate the virtual-to-physical address mapping).

In Step 606, the kernel module of the OS intercepts the page fault andforwards the page fault (and the associated write request) to the filesystem container of the node. In one embodiment of the invention, thekernel module may forward only the write request, as initially generatedby the application, to the file system container.

In one or more embodiments of the invention, as described in FIG. 1above, the kernel module is software executing in the OS that monitorsdata traversing the OS and may intercept, modify, and/or otherwise alterthat data based on one or more conditions. In one embodiment of theinvention, the kernel module is capable of redirecting data received bythe OS by intercepting and modifying that data to specify a recipientdifferent than normally specified by the OS.

In one or more embodiments of the invention, the OS will, initially, beconfigured to forward the page fault to the application from which therequest originated. However, in one embodiment of the invention, thekernel module detects the OS received a page fault, and instead forwardsthe page fault to a different location (i.e., the file system container)instead of the default recipient (i.e., the application container and/orapplication). In one embodiment of the invention, the kernel modulespecifically monitors for and detects exception handling processes thatspecify an application's inability to access the physical location ofdata.

In Step 608, the file system container, having received and processedthe page fault forwarded by the kernel module, informs the OS of theproper virtual-to-physical address mapping for the write request. Moredetails of the process of Step 608 are discussed in relation to FIG. 6Bbelow.

In Step 610, the OS initiates writing of the requested data to thehardware layer of the node. In one or more embodiments of the invention,the write request, initially generated by the application, is servicedby storing, in memory, the requested data.

Specifically, in one or more embodiments of the invention, afterreceiving the virtual-to-physical address mapping from the file systemcontainer in Step 608, the OS informs the hardware layer (the MMU,specifically) of the virtual-to-physical address mapping. In turn, theMMU creates an entry in the TLB that associates the virtual address (ofthe application's virtual address space) to the physical addressspecified by the file system container. Accordingly, when the MMUreceives any additional requests specifying that same virtual address,the MMU will then be able to locate the associated physical address inthe TLB (and therefore avoid issuing a page fault).

Thus, in one or more embodiments of the invention, after the TLBincludes the appropriate virtual-to-physical address mapping, the OSreissues and/or forwards the initial write request back to hardwarelayer of the node. Then, as the hardware layer is now configured toservice the request, the data is written to the physical addressspecified in the TLB (as identified by the file system container).

FIG. 6B shows a flowchart of a method for identifying a physicallocation to store new data, in accordance with one or more embodimentsof the invention. All or a portion of the method shown in FIG. 6B may beperformed by the file system container and/or the space manager thereof.While the various steps in this flowchart are presented and describedsequentially, one of ordinary skill in the relevant art will appreciatethat some or all of the steps may be executed in different orders, maybe combined or omitted, and some or all steps may be executed inparallel.

In Step 612, the file system container receives a write request to storenew data. As discussed above in Step 606, the file system container mayreceive a page fault (containing the write request) or the writerequest, alone, from a kernel module of the node. In one or moreembodiments of the invention, the space manager of the file systemcontainer, performs the processing of the write request.

In Step 614, the space manager identifies one or more available sparsevirtual space segments for the new data. In one or more embodiments ofthe invention, as described in Step 506 above, the space manager mayhave already allocated and associated every sparse virtual space segmentwith every available memory pool segment. However, in one or moreembodiments of the invention, the space manager may not associate sparsevirtual space segments with memory pool segments until receiving a writerequest.

In turn, in one or more embodiments of the invention, the space manageridentifies one or more sparse virtual space segments sufficiently largeenough (e.g., containing sufficient free space) to service the writerequest. If not already associated with memory pool segments, the spacemanager identifies one or more memory pool segments sufficiently largeenough (e.g., containing sufficient free space) to service the writerequest and associate those memory pool segments with available sparsevirtual space segments.

In one or more embodiments of the invention, once the one or more memorypool segments are identified, the associated one or more memory segmentsare identified based on a prior established mapping (see e.g., FIGS.4-5).

In Step 616, the file system container informs the OS of thevirtual-to-physical address mapping. In one or more embodiments of theinvention, once a physical address of the memory is known, the spacemanager generates a virtual-to-physical address mapping using thevirtual address received with the write request and the physical addressidentified in the memory pool.

In one or more embodiments of the invention, once thevirtual-to-physical address mapping is generated, the space managerinitiates the transmission of the virtual-to-physical address mapping tothe OS (to ultimately inform the MMU). As the space manager may be anisolated software instance executing within the file system container,the file system container may be the software instance that directlyforwards the mapping to the OS.

In one or more embodiments of the invention, the file system containermay also re-forward the write request back to the OS for servicing.Alternatively, in one embodiment of the invention, the OS may havetemporarily stored the write request, while the file system containergenerated and provided the virtual-to-physical address mapping, so thatthe write request could be resent upon the receipt of the correspondingvirtual-to-physical address mapping.

FIG. 7A shows a flowchart of a method for establishing direct access tomemory of the hardware layer of the node via a virtual-to-physicaladdress mapping, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 7A may beperformed by one or more components of the node. While the various stepsin this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In Step 700, an application issues a mapping request for data in thevirtual address space of that application. In one or more embodiments ofthe invention, the mapping request specifies the virtual address spacesegment (e.g., virtual address) of the virtual address space. In one ormore embodiments of the invention, the mapping request specifies thedata using a file identifier and a file offset. Further, in oneembodiment of the invention, as the data being directly accessed alreadyexists, it is assumed the physical location of the data is identifiable.

In one or more embodiments of the invention, a mapping request is arequest to establish a one-to-one mapping between one or more virtualaddress space segments and one or more memory segments (e.g., one ormore virtual-to-physical address mappings that directly correlateapplication virtual memory address(es) to physical memory address(es)).Further, in one embodiment of the invention, as mapping to a region ofmemory requires that data to be located on a byte-addressable device(i.e., memory), it is therefore not possible to establish a directmapping to data physically stored in persistent storage. That is,persistent storage is not configured to support, and is therefore notsuitable for, servicing mapping requests, and the requested data willtherefore need to be relocated to a suitable device in order toestablish the requested direct access mapping (as discussed in relationto FIG. 7B below)

In one or more embodiments of the invention, as described in FIG. 1above, the application may be executing within an application containerthat has the ability to access the OS of the node. Thus, when anapplication, isolated in an application container, issues a mappingrequest to an internal virtual address space, the application containerhandles that command before interacting with the OS.

In Step 702, the application container, to which the applicationbelongs, forwards the mapping request to the OS. In one or moreembodiments of the invention, although the application issued themapping request to the virtual address space of the application, suchinternal requests ultimately trigger external commands to the underlyingOS so that the request to the virtual address space may be serviced bythe hardware devices of the node.

In one or more embodiments of the invention, the application containerforwards the request, unaltered to the OS of the node. Alternatively, inone embodiment of the invention, the application container may modifythe request prior to forwarding, for example, by translating the virtualaddress specified by the application to another virtual address (in theevent of a known conflict) and/or otherwise modify the request toconform with the operations of the node.

In Step 704, a determination is made as to whether a page fault isissued by the hardware layer of the node. In one or more embodiments ofthe invention, the virtual address specified by the mapping request willalready be mapped to a physical address in the TLB with avirtual-to-physical address mapping. However, if the TLB lacks an entryassociating the virtual address to any physical address, the hardwarelayer issues a page fault as described in Step 604 above. If a pagefault is not issued (704—NO), the process proceeds to Step 710.Alternatively, if a page fault is issued (704—YES), the process proceedsto Step 706. In one or more embodiments of the invention, the page faultmay include the initial mapping request and an indication that thevirtual-to-physical address mapping does not exist in the TLB.

In Step 706, the kernel module intercepts and forwards the page fault tothe file system container. In one or more embodiments of the invention,as described in Step 606 above, the OS is initially configured toforward the page fault to the application from which the requestoriginally initiated. However, in one embodiment of the invention, thekernel module detects the OS received a page fault, and instead forwardsthe page fault to a different location (i.e., the file system container)instead of the default recipient (i.e., the application container and/orapplication). In one embodiment of the invention, the kernel modulespecifically monitors for and detects exception handling processes thatspecify an application's inability to access the physical location ofdata.

In Step 708, the file system container, having received and processedthe page fault forwarded by the kernel module, informs the OS of theproper virtual-to-physical address mapping for the write request. Moredetails of the process of Step 708 are discussed in relation to FIG. 7Bbelow.

In Step 710, the OS informs the application that a memory mapping hasbeen established. In one or more embodiments of the invention, themapping request, initially generated by the application, is serviced byinforming the MMU (and TLB) of the virtual-to-physical address mappingassociated with the virtual address specified by the application.

Specifically, in one or more embodiments of the invention, afterreceiving the virtual-to-physical address mapping from the file systemcontainer in Step 708, the OS informs the hardware layer (the MMU,specifically) of the virtual-to-physical address mapping. In turn, theMMU creates an entry in the TLB that associates the virtual address(initially specified by the application) to the physical addressspecified by the file system container. Accordingly, when the MMUreceives any additional requests specifying that same virtual address,the MMU will then be able to locate the associated physical address inthe TLB (and therefore avoid issuing a page fault).

Thus, in one or more embodiments of the invention, after the TLBincludes the appropriate virtual-to-physical address mapping, the OSinforms the application of the successful memory mapping. Accordingly,the hardware layer of the node is then configured to directly serviceany request referencing that virtual address. More detail on the directaccess to hardware layer components is discussed in FIGS. 8A and 8Bbelow.

FIG. 7B shows a flowchart of a method for identifying a physicallocation that satisfies the mapping request, in accordance with one ormore embodiments of the invention. All or a portion of the method shownin FIG. 7B may be performed by the file system container and/or thespace manager thereof. While the various steps in this flowchart arepresented and described sequentially, one of ordinary skill in therelevant art will appreciate that some or all of the steps may beexecuted in different orders, may be combined or omitted, and some orall steps may be executed in parallel.

In Step 712, the file system container receives a mapping request todata located in memory. As discussed above in Step 706, the file systemcontainer may receive a page fault (including the mapping request) orthe mapping request, alone, from a kernel module of the node. In one ormore embodiments of the invention, the space manager of the file systemcontainer processes the mapping request.

In Step 714, the space manager identifies one or more sparse virtualspace segments associated with the requested data. In one or moreembodiments of the invention, as discussed in Step 700 above, themapping request specifies the data using a file identifier and a fileoffset.

In one or more embodiments of the invention, the space manager uses thefile identifier to identify a logical volume and a logical volumeoffset, within that logical volume, associated with file identifier.Once the logical volume offset is known, the sparse virtual spacesegment(s) associated with that file are similarly identified. Further,using the specified file offset, one or more sparse virtual spacesegments are identified and located that are specific to the dataspecified in the received mapping request. Accordingly, at this point,the space manager has located, in the sparse virtual space, the dataspecified in the mapping request.

In Step 716, the space manager identifies the pools mapped to the one ormore sparse virtual space segments identified in Step 714. Further, inone or more embodiments of the invention, as the pools are categorizedinto two categories, memory pool(s) and persistent storage pool(s), thestorage type of the requested data is similarly identifiable.

In Step 718, the space manager determines the storage type of the deviceon which the requested data is located. As discussed in Step 716 above,in one embodiment of the invention, identifying the pool associated withthe sparse virtual space segment is sufficient to determine the storagetype of the device, as each pool is unique to the two types of storage(persistent storage and memory).

In one or more embodiments of the invention, mapping to a region ofmemory requires that data to be located on a byte-addressable device(i.e., memory). Accordingly, it is therefore not possible to establish adirect mapping to data physically located in persistent storage (storedin blocks). That is, persistent storage is not configured to support,and is therefore not suitable for, servicing mapping requests.

Accordingly, if the specified data of the mapping request is located inpersistent storage, the requested data is relocated to a suitable devicein order to establish the direct mapping. However, if the data isalready located on a device that is suitable for direct memory mapping(i.e., memory), the current location of that data is thereforesufficient to service the request, without first moving the data.

If the requested data is located in persistent storage (718—NO), theprocess proceeds to Step 720. Alternatively, if the requested data islocated in memory (718—YES), the process proceeds to Step 722.

In Step 720, the file system container initiates copying the data frompersistent storage to memory. Specifically, in one or more embodimentsof the invention, the space manager identifies the physical location ofthe requested data using the persistent storage pool(s). As described inFIG. 4 above, each identified persistent storage pool segment isassociated with persistent storage segments that identify the physicallocations of the requested data.

In one or more embodiments of the invention, once the physical locationof the requested data is known, the space manager identifies availablelocations of memory to relocate the data. Specifically, the spacemanager may analyze one or more memory pools and/or the sparse virtualspace to located regions of physical memory that are available (e.g.,includes sufficient free space) to copy to the requested data. The exacttype of memory chosen to relocate the data is irrelevant, in one or moreembodiments of the invention, the only relevant characteristic of thenew memory device is that byte-level manipulation be possible, therebyallowing for direct virtual-to-physical address mapping.

In one or more embodiments of the invention, once the physical locationof the requested data and the physical location of available memory areknown, the space manager generates a copy command to copy the data fromthe data's location in persistent storage to the new location in memory.Further, in one embodiment of the invention, as the requested data isstored in blocks in persistent storage, every block that includes therequested data will have to be copied, even though those blocks maycontain other, non-requested data. However, the copy command issued bythe space manager ensures only the requested data is copied to memory,and not all of the data from each entire block identified in persistentstorage.

Accordingly, in one or more embodiments of the invention, once the copycommand is generated by the space manager, the file system containerforwards that command to the OS to initiate copying of the data frompersistent storage to memory.

In Step 722, the file system container informs the OS of thevirtual-to-physical address mapping. In one or more embodiments of theinvention, once a physical address of the memory is known, the spacemanager generates a virtual-to-physical address mapping using thevirtual address received with the mapping request and the physicaladdress identified in the memory pool.

In one or more embodiments of the invention, once thevirtual-to-physical address mapping is generated, the space managerinitiates sending the virtual-to-physical address mapping to the OS (toultimately inform the MMU).

FIG. 8A shows a flowchart of a method for directly accessing a region ofmemory, in accordance with one or more embodiments of the invention. Allor a portion of the method shown in FIG. 8A may be performed by one ormore components of the node. While the various steps in this flowchartare presented and described sequentially, one of ordinary skill in therelevant art will appreciate that some or all of the steps may beexecuted in different orders, may be combined or omitted, and some orall steps may be executed in parallel.

In Step 800, an application issues a read request to the virtual addressspace of that application. In one or more embodiments of the invention,the read request specifies the virtual address space segment (e.g.,virtual address) of the virtual address space. Further, in oneembodiment of the invention, the application is aware that a memorymapping exists for the virtual address space segments being utilized.

In one or more embodiments of the invention, as described in FIG. 1above, the application may be executing within an application containerthat has the ability to access the OS of the node. Thus, when anapplication, isolated in an application container, issues a request toan internal virtual address space, the application container must handlethat command before interacting with the OS.

In Step 802, the application container, to which the applicationbelongs, forwards the read request to the OS. In one or more embodimentsof the invention, although the application issued the read request tothe virtual address space of the application, such internal requestsultimately trigger external commands to the underlying OS so that therequest to the virtual address space may be reflected in the hardwaredevices of the node.

In one or more embodiments of the invention, the application containerforwards the request, unaltered to the OS of the node. Alternatively, inone embodiment of the invention, the application container may modifythe request prior to forwarding, for example, by translating the virtualaddress specified by the application to another virtual address (in theevent of a known conflict) and/or otherwise modify the request toconform with the operations of the node.

In Step 804, the MMU of the hardware layer performs a lookup in the TLBto identify a physical address associated with the specified virtualaddress. In one or more embodiments of the invention, as described abovein Step 604, when a request to access or modify memory is sent to theMMU, using a virtual address, the MMU may perform a lookup in the TLB tofind a physical address associated with the provided virtual address(e.g., a virtual-to-physical address mapping).

In Step 806, the MMU identifies the physical address(es) associated withthe virtual address of the read request. Specifically, in one embodimentof the invention, where the application had already established a directmapping (e.g., the process of FIGS. 7A and 7B), the MMU locates thealready-existing virtual-to-physical address mapping in the TLB.However, if for some reason, the virtual-to-physical address mappingdoes not exist in the TLB, the MMU initiates a page fault and theprocess described in Steps 704-710 are performed.

In Step 808, the MMU reads the data at the physical addresses specifiedby the TLB. In one or more embodiments of the invention, the MMUtransmits that data to one or more processors (and the cache therein)for temporary storage while being read by the application.

In Step 810, one or more processors receives the data from memory, viathe MMU. In one or more embodiments of the invention, a processor storesthat data in the cache local to the processor for more rapid reading andmanipulation. Further, once in cache, the processor may provide the datato the application, as initially requested.

FIG. 8B shows a flowchart of a method for directly writing to a regionof memory, in accordance with one or more embodiments of the invention.All or a portion of the method shown in FIG. 8B may be performed by oneor more components of the node. While the various steps in thisflowchart are presented and described sequentially, one of ordinaryskill in the relevant art will appreciate that some or all of the stepsmay be executed in different orders, may be combined or omitted, andsome or all steps may be executed in parallel.

In Step 812, an application issues a write request to store new data inthe virtual address space of that application (or overwrite/modifyexisting data in the virtual address space). In one or more embodimentsof the invention, the write request specifies the virtual address spacesegment (e.g., virtual address) of the virtual address space and thedata to be written to the associated virtual address space segment.Further, in one embodiment of the invention, the application is awarethat a memory mapping exists for the utilized virtual address spacesegments.

In one or more embodiments of the invention, as described in FIG. 1above, the application may be executing within an application containerthat has the ability to access the OS of the node. Thus, when anapplication, isolated in an application container, issues a request toan internal virtual address space, the application container must handlethat command before interacting with the OS.

In Step 814, the application container, to which the applicationbelongs, forwards the write request to the OS. In one or moreembodiments of the invention, although the application issued the writerequest to the virtual address space of the application, such internalrequests ultimately trigger external commands to the underlying OS sothat the request to the virtual address space may be reflected in thehardware devices of the node.

In one or more embodiments of the invention, the application containerforwards the request, unaltered to the OS of the node. Alternatively, inone embodiment of the invention, the application container may modifythe request prior to forwarding, for example, by translating the virtualaddress specified by the application to another virtual address (in theevent of a known conflict) and/or otherwise modify the request toconform with the operations of the node.

In Step 816, the processor writes the requested data to the cache. Inone or more embodiments of the invention, the processors receives thewrite request issued by the application and processes that new data (orchanges to existing data) in the local cache of the processor. That is,even though the application specified a virtual address which is mappedto a physical address of memory, the processor may first internallystores and processes the changes requested by the application. In oneembodiment of the invention, when data is located in cache, instead ofits intended location in memory and/or persistent storage, that data maybe considered “uncommitted” or “dirty”. Further, in one embodiment ofthe invention, the application is unaware of whether the data sent inthe write request is stored in cache or in the intended physicallocation of memory (associated with the virtual address).

In Step 818, the processor initiates of copy of the new data (of thewrite request) to memory via the MMU. In one or more embodiments of theinvention, the cache is a limited resource (e.g., little total space)and may therefore reach a maximum capacity more quickly than otherdevices of the hardware layer. In the event the cache is determined tobe too full, the processor begins copying certain data from the internalcache to the location originally specified by the request. Thedetermination of which data in the cache to copy to memory may be basedon one or more characteristics including, but not limited to, which datais least recently used, which data is least frequently used, and/or anyother characteristic for determining which data may be least useful tomaintain in cache. In one or more embodiments of the invention, theprocessor issues a write request to the MMU that includes the modifieddata and the virtual address specified by the application.

Further, in one embodiment of the invention, the application is unawareof when the processor copies data from cache to memory resulting from adetermination that the cache is too full. And, therefore, theapplication is unaware of whether the data sent in the write request isstored in cache or in the intended physical location of memory(associated with the virtual address).

In Step 820, the MMU of the hardware layer performs a lookup in the TLBto identify a physical address associated with the specified virtualaddress of the write request. In one or more embodiments of theinvention, as described above in Step 604, when a request to access ormodify memory is sent to the MMU, using a virtual address, the MMU mayperform a lookup in the TLB to find a physical address associated withthe provided virtual address (e.g., a virtual-to-physical addressmapping).

In Step 822, the MMU identifies the physical address(es) associated withthe virtual address of the write request. Specifically, in oneembodiment of the invention, where the application had alreadyestablished a direct mapping (e.g., the process of FIGS. 7A and 7B), theMMU locates the already-existing virtual-to-physical address mapping inthe TLB. However, if for some reason, the virtual-to-physical addressmapping does not exist in the TLB, the MMU initiates a page fault andthe process described in Steps 704-710 are performed.

In Step 824, the MMU copies the data of the write request to thephysical addresses specified in the TLB. In one or more embodiments ofthe invention, after the MMU finishes copying the data to memory, theMMU informs the processor of a successful write. Further, in oneembodiment of the invention, the processor may consequently inform theOS that the data was successfully copied to memory, and the OS mayinform the application that the data was successfully written to memory.

FIG. 9A shows a flowchart of a method for syncing data changes of amemory mapped region, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 9A may beperformed by one or more components of the node. While the various stepsin this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In Step 900, an application issues a sync command for data that has beendirectly manipulated in memory. In one or more embodiments of theinvention, the application is unaware as to whether the data sent inprevious write requests has been persisted (e.g., copied) to thephysical address(es) of memory associated with the virtual address(es)of the write requests (e.g., whether that data is uncommitted).Accordingly, to force the potentially uncommitted data to be committed(i.e., copied to memory, e.g., PMem), the application may issue a synccommand to instruct the processor to force any uncommitted data, locatedin cache, to memory.

In one or more embodiments of the invention, as described in FIG. 1above, the application may be executing within an application containerthat has the ability to access the OS of the node. Thus, when anapplication, isolated in an application container, issues a request toan internal virtual address space, the application container must handlethat command before interacting with the OS.

In Step 902, the application container, to which the applicationbelongs, forwards the write request to the OS. In one or moreembodiments of the invention, the application container forwards thecommand, unaltered to the OS of the node. Alternatively, in oneembodiment of the invention, the application container may modify thecommand prior to forwarding, for example, by translating the virtualaddress specified by the application to another virtual address (in theevent of a known conflict) and/or otherwise modify the command toconform with the operations of the node.

In Step 904, the kernel module of the OS intercepts and forwards thesync command to the file system container of the node. In one or moreembodiments of the invention, in contrast to Steps 606 and 706, thekernel module intercepts the sync command from the application beforebeing passed to the hardware layer of the node. Specifically, in oneembodiment of the invention, the kernel module is configured to identifysync commands and redirect those commands to a new destination (i.e.,the file system container).

In Step 906, the file system container, having received and processedthe sync command forwarded by the kernel module, re-initiates the syncprocess by forwarding one or more sync commands back to the OS. Moredetails of the process of Step 906 are discussed in relation to FIG. 9Bbelow.

In Step 908, the processor receives the sync command and initiates thecopying of the relevant uncommitted data to memory. In one or moreembodiments of the invention, the processor identifies the dataassociated with the sync command and initiates the copying of theidentified data, to memory. As described in Steps 820, 822, and 824above, the MMU receives the write request, perform a lookup in the TLB,identify the associated physical address(es) in memory for the writerequest, copy the uncommitted data to the associated physicaladdress(es), then inform the processor of the successful writing of thedata. In turn, in one embodiment of the invention, the processor theninforms the OS of the successful writing of the data indicated by thesync command to memory; and the OS informs the application that the datawas successfully written to memory.

FIG. 9B shows a flowchart of a method for servicing a sync command, inaccordance with one or more embodiments of the invention. All or aportion of the method shown in FIG. 9B may be performed by the filesystem container and/or the space manager thereof. While the varioussteps in this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In Step 910, the file system container receives a sync command for datathat was being directly manipulated by the application. In one or moreembodiments of the invention, the space manager may modify the synccommand consistent with the physical addresses identified in one or morememory pool(s). Further, the sync command may be modified such that thekernel module will not, again, intercept the sync command whentraversing the OS. In one embodiment of the invention, if one or morememory pool segments associated with the sync command are associatedwith two or more memory segments, the space manager may generateadditional sync commands to duplicate the changes in data to thoseadditional memory segments.

In Step 912, the file system container forwards the sync command(s) tothe OS in order to commit the data, located in cache, to memory. In oneor more embodiments of the invention, the sync command may be the samesync command as originally received by the file system container, oralternatively be modified consistent with the one or more determinationsof Step 910.

FIG. 10 shows an example in accordance with one or more embodiments ofthe invention. The following use case is for explanatory purposes onlyand not intended to limit the scope to this embodiment.

In FIG. 10, consider a scenario in which, at (1), application (1012)issues a mapping request for data in virtual address space (1020) toestablish direct access to memory (1038). The mapping request specifiesa virtual address of the virtual address space (1020) and specific datausing a file identifier and a file offset.

At (2), application container (1002) forwards the mapping request to theOS (1008). Here, the application container (1002) forwards the request,unaltered to the OS (1008) of the node (1000). Further, the OS (1008)passes the mapping request to hardware layer (1010) of the node (1000)without any additional processing.

At (3), the processor (1034) receives the mapping request in thehardware layer (1010) and forwards the request to the MMU (1040). At(4), the MMU (1040) performs a lookup in TLB (1041) to locate a physicaladdress associated with the virtual address of the mapping request.However, the TLB (1041) does not contain a virtual-to-physical addressmapping for the specified virtual address. Accordingly, the MMU (1040)issues a page fault to the OS (1008) that includes the mapping request.

At (5), the kernel module (1030) detects a page fault in the OS (1008)and interrupts normal handling of the page fault by the OS (1008).Specifically, the kernel module (1030) intercepts the page fault andforwards the mapping request (of the page fault) to the file systemcontainer (1006).

At (6), the space manager (1028) of the file system container (1006)receives the mapping request and locates the file in the sparse virtualspace by analyzing the file identifier to identify a logical volume anda logical volume offset, within that logical volume, associated withfile identifier. Once the logical volume offset is known, the sparsevirtual space segments associated with that file are similarlyidentified. Further, using the specified file offset, the space manager(1028) identifies and locates the sparse virtual space segment specificto the data specified in the received mapping request.

Further, at (6), the space manager (1028) identifies that the sparsevirtual space segment is associated with memory pool segment, which inturn, is directly associated with a memory segment (and correspondingphysical address). The space manager (1028) then generates and initiatesthe transmission of a virtual-to-physical address mapping that specifiesthe virtual address of the mapping request and the physical addressidentified from the memory pool segment.

At (7), the file system container (1006) forwards thevirtual-to-physical address mapping to the MMU (1040). In one or moreembodiments of the invention, the file system container (1006) transmitsthe virtual-to-physical address mapping to hardware layer (1010) via theOS (1008).

At (8), the MMU (1040) writes a new entry to the TLB (1041)corresponding to the virtual-to-physical address mapping received fromthe file system container (1006). After the MMU (1040) writes the entryinto the TLB (1041), the MMU (1040) additionally informs the OS (1008)that the memory mapping was successful. In turn the OS (1008) informsthe application container (1002) and the application (1012) that thememory mapping request was successfully serviced and direct access hasbeen established.

FIG. 11 shows an example in accordance with one or more embodiments ofthe invention. The following use case is for explanatory purposes onlyand not intended to limit the scope to this embodiment.

In FIG. 11, consider a scenario in which, at (1), application (1112)issues a write request to overwrite existing data in virtual addressspace (1120) for which direct access to memory (1138) has already beenestablished. The write request specifies a virtual address and thechanges to the data.

At (2), application container (1102) forwards the write request to theOS (1108). Here, the application container (1002) forwards the request,unaltered to the OS (1108) of the node (1100). Further, the OS (1108)passes the write request to hardware layer (1110) of the node (1100)without any additional processing.

At (3), the processor (1134) receives the write request in the hardwarelayer (1110), stores the data changes to cache (1135), and forwards therequest to the MMU (1140). At (4), the MMU (1140) performs a lookup inTLB (1141) to locate a physical address associated with the virtualaddress of the mapping request. The TLB (1141) then successfullyidentifies and returns to the MMU (1140) the physical address associatedwith the virtual address. The MMU (1140) then copies the data changesfrom cache (1135) to the physical location in memory (1138) specified bythe physical address found in the TLB (1141). Specifically, in thiscase, the data is written to some portion of PMem N.

FIG. 12 shows an example in accordance with one or more embodiments ofthe invention. The following use case is for explanatory purposes onlyand not intended to limit the scope to this embodiment.

In FIG. 12, consider a scenario in which, at (1), application (1212)issues a sync command for data being manipulated in the virtual addressspace (1220) via direct access to memory (1238). The sync commandspecifies a virtual address of the virtual address space (1220) and themodified data.

At (2), application container (1002) forwards the sync command to the OS(1208). Here, the application container (1202) forwards the request,unaltered to the OS (1208) of the node (1200). At (3), the kernel module(1230) detects the sync command in the OS (1208) and interrupts normalhandling of the sync command by the OS (1208). Specifically, the kernelmodule (1230) intercepts the sync command and forwards the sync commandto the file system container (1206).

At (4), the space manager (1228) of the file system container (1206)receives the sync command and identifies each memory segment affected bythe sync command. Then, after identifying that PMem N is only affectedmemory (1238) device, space manager (1228) analyzes the sync command toensure that the sync command properly specifies copying data to correctphysical locations. The space manager (1228) then regenerates the synccommand consistent with the physical locations identified in the memorypool.

At (5), the file system container (1206) forwards the sync command tothe processor (1234) through OS (1208). At (6), processor (1234)receives the sync command and identifies all relevant uncommitted dataassociated with the sync command, in cache (1235), to be copied tomemory (1238). Processor (1234) then initiates copying the identifieduncommitted data to memory by sending a write request to the MMU (1240)to copy the data to memory (1238).

At (7), the MMU (1240) performs a lookup in TLB (1241) to locate aphysical address associated with the virtual address of the writerequest from the processor (1234). The TLB (1241) then successfullyidentifies and returns, to the MMU (1240), the physical addressassociated with the virtual address. The MMU (1240) then copies the datafrom cache (1235) to the physical location in memory (1238) specified bythe physical address found in the TLB (1241). Specifically, in thiscase, the data is written to some portion of PMem N.

FIG. 13 shows a diagram of a cluster (1300) in accordance with one ormore embodiments of the invention. In one embodiment of the invention,cluster (1300) includes one or more node(s) (e.g., node H (1302), node I(1304), node J (1306)). The node(s) (1302, 1304, 1306) shown in FIG. 13have all of the same properties and functionalities as discussed in thedescription of FIG. 2.

In one or more embodiments of the invention, a cluster (e.g., cluster(1300)) is a collection of two or more operatively connected node(s)(1302, 1304, 1306). Node(s) (1302, 1304, 1306) of cluster (1300) may beoperatively connected via the same LAN, operatively connected via a WAN,or grouped within several LANs, each of which is operatively connectedvia a WAN. One of ordinary skill in the art, having the benefit of thisdetailed description, will appreciate that the node(s) (1302, 1304,1306) may be operatively connected via one or more forms ofcommunication.

In one or more embodiments of the invention, node(s) (1302, 1304, 1306)may be grouped within a cluster (e.g., cluster (1300)) based on one ormore characteristics of the node(s) (1302, 1304, 1306). For example,nodes (1302, 1304, 1306) may be within cluster (1300) due to theiroperations being mutually dependent upon access to the other nodes(1302, 1304, 1306) of the cluster (1300). Alternatively, as an example,node(s) (1302, 1304, 1306) may be within cluster (1300) due to theircommon ownership and desire for nodes (1302, 1304, 1306) to beoperatively connected.

In one or more embodiments of the invention, nodes (1302, 1304, 1306)may be operatively connected via the communication interface(s) locatedwithin each node. Nodes (1302, 1304, 1306) may utilize one or moreprotocols to enable the communication of one or more components withineach node. For example, each node (1302, 1304, 1306) of cluster (1300)may be operatively connected, via Ethernet, using a TCP/IP protocol toform a “network fabric” and enable the communication of data betweennodes. In one or more embodiments of the invention, each node within acluster may be given a unique identifier (e.g., an IP address) to beused when utilizing one or more protocols.

Further, in one or more embodiments of the invention, the implementationof certain protocols (e.g., TCP/IP) may enable specific protocolvariants that allow for the direct access to memory of other,operatively connected, nodes (i.e., RDMA) and thus form a “memoryfabric”. Additionally, in one or more embodiments of the invention,nodes (1302, 1304, 1306) may be alternatively, or additionally,operatively connected via, for example, fiber optic connections to forma “fiber optic fabric” to enable the communication of data between nodes(1302, 1304, 1306). One of ordinary skill in the art, having the benefitof this detailed description, will appreciate that the node(s) (1302,1304, 1306) of cluster (1300) may be connected via one or more physicalnetwork interfaces, using one or more protocols, to enable thecommunication of data from one or more components of the hardware layerof any node (1302, 1304, 1306) within the cluster (1300).

Further, in one embodiment of the invention, when using certain aprotocol or variant thereof, streamlined access to certain components ofother nodes (1302, 1304, 1306) becomes possible. For example, whenutilizing RDMA to access the data on another node (1302, 1304, 1306), itmay not be necessary to interact with the software of that other node(1302, 1304, 1306). Rather, when using RDMA, it may be possible for onenode (1302, 1304, 1306) to interact only with the hardware elements ofthe other node (1302, 1304, 1306) to retrieve and/or transmit data,thereby avoiding any higher-level processing by the software executingon that other node (1302, 1304, 1306).

Alternatively, in one or more embodiments of the invention, nodes (1302,1304, 1306) of cluster (1300) interact with, initiate, alter, and/orcontrol the software (containers, applications, OS) executing on othernodes. Thus, in one or more embodiments of the invention, thecommunication between nodes (1302, 1304, 1306) of cluster (1300) is notlimited to the sharing of stored data in the hardware layer of each node(1302, 1304, 1306). Rather, nodes (1302, 1304, 1306) may communicateinstructions related to the execution of software including, forexample, requesting the space manager of another node (1302, 1304, 1306)provide information or initiate a process on that other node (1302,1304, 1306). Accordingly, in one embodiment of the invention, a node(1302, 1304, 1306) may outsource the processing of one or more softwaretasks to another node (1302, 1304, 1306).

In one or more embodiments of the invention, a node (1302, 1304, 1306)may be considered an “independent fault domain”. Specifically, as a node(1302, 1304, 1306), in one embodiment of the invention, includes allcomponents necessary to function inside the node (1302, 1304, 1306)itself, the failure of a node (1302, 1304, 1306) may not result in thefailure of other nodes (1302, 1304, 1306). Thus, for example, while twoor more nodes (1302, 1304, 1306) may communicate to form a cluster(1300), every individual node (1302, 1304, 1306) within that cluster(1300) may continue to operate upon the failure of every other node(1302, 1304, 1306) (although the functioning of one or more node(s) maybe altered due to the failure of another node).

While FIG. 13 shows a specific configuration of a cluster, otherconfigurations may be used without departing from the scope of thedisclosure. Accordingly, embodiments disclosed herein should not belimited to the configuration of devices and/or components shown in FIG.13.

FIG. 14 shows an example of one embodiment of a local node (1400) and aremote node (1442). In one embodiment of the invention, local node(1400) includes an application container (1402) with application (1412)and virtual address space (1420), a file system container (1406) withspace manager (1428), an OS (1408) with kernel module (1430), and ahardware layer (1410) with communication interface (1432), localpersistent storage (1436), and local memory (1438). In one embodiment ofthe invention, remote node (1442) includes a file system container(1444) with space manager (1450), an OS (1446) with kernel module(1452), and a hardware layer (1448) with communication interface (1454),remote persistent storage (1456), and remote memory (1458). Similarlynamed parts shown in FIG. 14 have all of the same properties andfunctionalities as described above in FIG. 2. Accordingly, onlyadditional properties and functionalities are described below.

In one or more embodiments of the invention, local persistent storage(1436) and local memory (1438) may be considered “local” due to theirphysical location within the local node (1400). Accordingly, in one ormore embodiments of the invention, local node (1400) is configured toaccess local persistent storage (1436) and/or local memory (1438), viathe circuitry internal to the hardware layer (1410) of the local node(1400) without using the communication interface (1432). Alternatively,remote persistent storage (1456) and remote memory (1458) may beconsidered “remote”, from the perspective of local node (1400), due totheir physical location outside of local node (1400). Thus, in one ormore embodiments of the invention, local node (1400) is configured toaccess remote persistent storage (1456) and remote memory (1458) via thecommunication interfaces (1432, 1454) of local node (1400) and remotenode (1442).

One of ordinary skill in the art, having the benefit of this detaileddescription, will appreciate that terms “local” and “remote” arerelative to the perspective of the node (1400, 1442) performing thedescribed operation. In the example shown in FIG. 14, the adjectives“local” and “remote” are assuming the perspective of the local node(1400). Thus, for example, while labeled “remote memory” (1458), theremote node (1442) is able to access remote memory (1458) as though theremote memory (1458) were “local” (as usage of the communicationinterface (1454) is not required).

In one or more embodiments of the invention, local node (1400) andremote node (1442) are operatively connected via communication interface(1432) and communication interface (1454). In one embodiment of theinvention, the operative connection may be, for example, an Ethernetconnection between the local node (1400) and remote node (1442) whichallows for the communication of one or more components of the node.Accordingly, the operative connection between local node (1400) andremote node (1442) enables local node (1400) to access remote persistentstorage (1456) and remote memory (1458) of remote node (1442).Conversely, the operative connection between remote node (1442) andlocal node (1400) enables remote node (1442) to access local persistentstorage (1436) and local memory (1438) of local node (1400).

While FIG. 14 shows a specific configuration of a cluster, otherconfigurations may be used without departing from the scope of thedisclosure. For example, while FIG. 14 shows a remote node without anapplication or application container, one of ordinary skill in the art,having the benefit of this detailed description, will appreciate thatthe remote node may include some or all of the components of a nodedescribed in FIG. 2. Similarly, although the local node (1400) and theremote node (1442) are shown without processor(s), the local node (1400)and the remote node (1442) may still include all of the components asdiscussed in the description of FIG. 2. Accordingly, embodimentsdisclosed herein should not be limited to the configuration of devicesand/or components shown in FIG. 14.

FIG. 15 shows a diagram of a virtual-to-physical segment hierarchy inaccordance with one or more embodiments of the invention. In oneembodiment of the invention, the virtual-to-physical segment hierarchyincludes a virtual address space (1520), a sparse virtual space (1500),one or more memory pool(s) (1502), one or more persistent storagepool(s) (1504), local memory (1538), and remote memory (1540).

Similarly named parts shown in FIG. 15 have all of the same propertiesand functionalities as described in FIG. 4. Accordingly, only additionalproperties and functionalities are described below.

In one or more embodiments of the invention, memory pool(s) (1502) maybe associated with both local memory (1538) and remote memory (1540). Inone embodiment of the invention, one or more memory pools segment(s)(1510) (of memory pool (1502)) are associated with one or more localmemory segment(s) (of local memory (1538)) while other memory poolsegments (1510), of the same memory pool (1510), are associated with oneor more remote memory segment(s) (1542) (of remote memory (1540)).Accordingly, in one embodiment of the invention, the physical memorydevices (e.g., local memory (1538), remote memory (1540), etc.) that areassociated with a memory pool (e.g., memory pool (1502)) may bephysically located in two or more nodes.

In one or more embodiments of the invention, although the physicalmemory devices (e.g., local memory (1538), remote memory (1540), etc.),may be located in two or more nodes, the management of the sparsevirtual space (1500) and memory pool(s) (1502) remains local to the node(as managed by the space manager). For example, although the memory pool(1502) may be associated with one or more remote memory devices (e.g.,remote memory (1540)) located on one or more remote nodes, themanagement of the memory pool (1502) and its association to the remotememory (e.g., remote memory (1540)) is maintained locally without theneed to interface and/or interact with the space manager of the node onwhich the remote memory is physically located.

Further, as discussed in the description of FIG. 13 and FIG. 14, in oneor more embodiments of the invention, the local node may access remotememory (1540) through a communication interface of the hardware layer.Thus, although managed by one or more memory pool(s) (1502), the methodfor actually obtaining the data from one or more remote memorysegment(s) (1542) may necessitate the use of additional hardware andprotocols. Thus, even though locally mapped, the memory device (remotememory (1540)) still considered “remote”.

Similarly, although not shown in FIG. 15, persistent storage pool(s)(1504) may similarly be associated with one or more local persistentstorage devices (not shown) and one or more remote persistent storagedevices (not shown). Accordingly, all of the description relating to thememory pool(s) (1502), local memory (1538), and remote memory (1540)above similarly applies with respect to persistent storage pool(s)(1504), local persistent storage (not shown), and remote persistentstorage (not shown), respectively.

As discussed in the description of FIG. 4, one of ordinary skill in theart, having the benefit of this detailed description, will appreciatethat memory pool(s) (1502) may be organized by any suitablecharacteristic of the underlying memory (e.g., based on individual size,collective size, type, speed, etc.). Further, in one or more embodimentsof the invention, memory pool(s) (1502) and persistent storage pool(s)(1504) may also be categorized, created, and/or otherwise organizedbased on, at least, the physical location of the underlying device(local memory (1538), remote memory (1540), local persistent storage(not shown), remote persistent storage (not shown)).

For example, there may exist a memory pool (e.g., memory pool (1502))that is exclusively associated with remote memory devices (e.g., remotememory (1540)), while another memory pool (e.g., memory pool (1502)) maybe associated exclusively with local memory devices (e.g., local memory(1538)). Further, the physical location characteristic of the physicaldevice may be just one of two or more characteristic upon which the pool(e.g., memory pool(s) (1502) and persistent storage pool(s) (1504)) maybe organized. For example, there may exist a memory pool (e.g., memorypool (1502)) that is associated exclusively with remote DRAM memorydevices, or remote DRAM memory devices of a particular remote node. Oneof ordinary skill in the art, having the benefit of this detaileddescription, will appreciate that the pools (e.g., memory pool(s)(1502), persistent storage pool(s) (1504), etc.) may be organized by oneor more suitable characteristics of the underlying memory (e.g.,physical location, individual size, collective size, type, speed, etc.).

While FIG. 15 shows a specific configuration of a virtual-to-physicalsegment hierarchy, other configurations may be used without departingfrom the scope of the disclosure. Accordingly, embodiments disclosedherein should not be limited to the configuration of devices and/orcomponents shown in FIG. 15.

FIG. 16 shows a flowchart of a method for establishing direct access tomemory of the hardware layer of the node via a virtual-to-physicaladdress mapping, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 16 may beperformed by one or more components of a node. While the various stepsin this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In one or more embodiments of the invention, the method of FIG. 16 issubstantially similar to the method disclosed in FIG. 7A. Accordingly,in one embodiment of the invention, similarly disclosed steps in FIG. 16have all of the same properties and purpose as described above in FIG.7A. Accordingly, only differing and/or additional properties andprocesses are described below.

After the competition of Step 1606 (similar to Step 706, where thekernel module intercepts and forwards the page fault to the file systemcontainer), the process proceeds to Step 1608. Like Step 708 of FIG. 7A,in Step 1608 of FIG. 16, the file system container identifies thephysical location of the data and inform the OS of thevirtual-to-physical address mapping. However, unlike Step 708 of FIG.7A, in Step 1608 of FIG. 16, the file system container may determinethat the physical location of the requested data is located on a remotenode, and may therefore need to request and retrieve a copy of that data(to local memory) prior to informing the OS of the virtual-to-physicaladdress mapping. More details of the process of Step 1608 are discussedin relation to FIG. 17 below.

FIG. 17 shows a flowchart of a method for identifying a physicallocation that satisfies the mapping request, in accordance with one ormore embodiments of the invention. All or a portion of the method shownin FIG. 17 may be performed by the file system container and/or thespace manager thereof. While the various steps in this flowchart arepresented and described sequentially, one of ordinary skill in therelevant art will appreciate that some or all of the steps may beexecuted in different orders, may be combined or omitted, and some orall steps may be executed in parallel.

In Step 1700, the file system container receives a mapping request ordata. As discussed above in Step 706, the file system container mayreceive a page fault (including the mapping request) or the mappingrequest, alone, from a kernel module of the node. In one or moreembodiments of the invention, the space manager of the file systemcontainer processes the mapping request.

In Step 1702, the space manager determines if the data referenced in themapping request is managed by the space manager (e.g., mapped by thelocal node). In one or more embodiments of the invention, as discussedin Step 700 above, the mapping request may specify the data using a fileidentifier and a file offset.

In one or more embodiments of the invention, the space manager uses thefile identifier to identify a logical volume associated with that fileidentifier. Specifically, the space manager may perform a look up thefile identifier in a list of logical volumes (e.g., a file systemstructure) to identify the logical volume to which the specified filebelongs. Once the logical volume is known, the space manager thendetermines whether the logical volume is managed by the local spacemanager (e.g., associated with the local sparse virtual space).

In one embodiment of the invention, where the logical volume is managedby the space manager (1702—YES), the process proceeds to Step 1704. Inone or more embodiments of the invention, the method of Step 1702—YES issubstantially similar to the method discussed in description of FIG. 7B.Accordingly, in one embodiment of the invention, similarly disclosedprocesses of Step 1702—YES have all of the same properties and purposeas described for FIG. 7B.

Alternatively, if the logical volume identified by the space manager isnot managed by the file system container of the local node (1702—NO),the space manager needs to perform additional processes beforeidentifying the physical location of the requested data. In one or moreembodiments of the invention, the local space manager determines theremote node that manages that logical volume based on the identificationof the logical volume to which the file is associated. Accordingly, ifthe data is not locally managed (1702—NO), the process proceeds to Step1720.

In Step 1704, the space manager identifies one or more sparse virtualspace segments associated with the requested data. In one or moreembodiments of the invention, the method of Step 1704 is substantiallysimilar to the method discussed in description of Step 714. Accordingly,in one embodiment of the invention, similarly disclosed processes ofStep 1704 have all of the same properties and purpose as described forStep 714. After Step 1704, the process proceeds to Step 1706.

In Step 1706, the space manager identifies the pools mapped to the oneor more sparse virtual space segments identified to be associated withthe requested data. In one or more embodiments of the invention, themethod of Step 1706 is substantially similar to the method discussed indescription of Step 716. Accordingly, in one embodiment of theinvention, similarly disclosed processes of Step 1706 have all of thesame properties and purpose as described for Step 716.

In Step 1708, the space manager determines if the data associated withthe identified pool is located on a local device or a remote device. Inone or more embodiments of the invention, as discussed in thedescription of FIG. 15, a locally managed pool (e.g., memory pool orpersistent storage pool) may be associated with a remote device (e.g.,remote memory or remote persistent storage, respectively). Thus,although locally managed, the local node may need to first retrieve thedata from the remote location before servicing the mapping request.

If the data is located on a remote device (1708—YES), the processproceeds to Step 1712. Alternatively, if the data is located on a localdevice (1708—NO), the process proceeds to Step 1710.

In Step 1710, the space manager determines if the data is located inlocal device that is suitable for servicing the mapping request. In oneor more embodiments of the invention, after the space manager hasdetermined that the data specified in the mapping request is bothlocally managed (1702—YES) and locally stored (1708—NO), the spacemanager then needs to determine if the location of the data in the localdevice is capable of servicing the mapping request (e.g., if it ismemory) and further whether that memory is sufficiently suitable.

As discussed in Step 716 above, in one embodiment of the invention,identifying the pool associated with the sparse virtual space segment issufficient to determine the storage type of the device, as each pool isunique to the two types of storage (persistent storage or memory).

In one or more embodiments of the invention, mapping to a region ofmemory requires that data to be located on a byte-addressable device(i.e., memory). Accordingly, it is therefore not possible to establish adirect mapping to data physically located in persistent storage (storedin blocks). That is, persistent storage is not configured to support,and is therefore not suitable for, servicing mapping requests.Accordingly, if the specified data of the mapping request is located inpersistent storage, the requested data is relocated to a suitable devicein order to establish the direct mapping. Thus, in one or moreembodiments of the invention, if the data is already located on a devicethat is suitable for direct memory mapping (i.e., memory), the currentlocation of that data may therefore be considered sufficient to servicethe request, without first moving the data.

However, in one embodiment of the invention, the space manager may makean additional determination as to the suitability of the memory on whichthe data is currently located. For example, although it may be possibleto service a mapping request using the memory device on which the datais located (as the device is byte-addressable), that particular memorydevice may not be the most preferable available memory device on whichto allow for direct data manipulation. Specifically, in one or moreembodiments of the invention, certain memory devices may havecharacteristics (e.g., lower life expectancy, lower read/writethreshold, slower performance, lacking persistence) than other availablememory devices and therefore may not be considered ‘suitable’ forservicing the mapping request. Accordingly, in one embodiment of theinvention, if the data is located on a memory device that is notconsidered suitable, the space manager may initiate copying of that datato a different memory device.

If the requested data is located in persistent storage or non-suitablelocal memory (1710—NO), the process proceeds to Step 1712.Alternatively, if the requested data is located in suitable memory(1710—YES), the process proceeds to Step 1714.

In Step 1712, the space manager initiates copying of the requested datafrom its identified location to a location on a suitable local memorydevice. In one or more embodiments of the invention, the method of Step1712 is substantially similar to the method discussed in description ofStep 720. Accordingly, in one embodiment of the invention, similarlydisclosed processes of Step 1712 have all of the same properties andpurpose as described for Step 720. Accordingly, only differing and/oradditional properties and processes are described below.

In one or more embodiments of the invention, in the instance where thedata is located on a remote node, the space manager initiates a copy ofthe data using one or more communication interface(s) of the node. Inone embodiment of the invention, of the invention, the space manager (ofthe local node) is able to generate a command to copy the data directlyfrom the memory device of the remote node without interacting with thesoftware of the remote node (i.e., via RDMA).

In one or more embodiments of the invention, in the instance where datais located in a non-suitable local memory location, the space managerinitiates copying of the data from the non-suitable memory location to asuitable memory location. Specifically, the space manager may analyzeone or more memory pools and/or the sparse virtual space to locateregions of suitable physical memory that are available (e.g., includessufficient free space) to copy to the requested data.

In one or more embodiments of the invention, once the physical locationof the requested data and the physical location of available memory areknown, the space manager generates a copy command to copy the data fromthe data's location in persistent storage to the new location in memory.

Accordingly, in one or more embodiments of the invention, once the copycommand is generated by the space manager, the file system containerforwards that command to the OS to initiate copying of the data frompersistent storage to memory.

In Step 1714, the file system container informs the OS of thevirtual-to-physical address mapping. In one or more embodiments of theinvention, the method of Step 1714 is substantially similar to themethod discussed in description of Step 722. Accordingly, in oneembodiment of the invention, similarly disclosed processes of Step 1714have all of the same properties and purpose as described for Step 722.

In Step 1720, the space manager determines if the method for receivingthe data should be via requesting the data layout (the memory and/orpersistent storage pool associations to underlying physical locations ofthe data) from the remote node (and initiating the copying of the datalocally), or whether the data should be received by requesting theremote node to initiate the copying of the data. In one or moreembodiments of the invention, both methods result in the requested databeing copied to a local memory device. The determination for choosingwhich method to request and receive the data may be based on, forexample, characteristics of either node (e.g., current operatingthreshold, capabilities, configuration, etc.).

If the data is to be received via the use of a data layout (1720—YES),the process proceeds to Step 1722. Alternatively, if the data is to bereceived by requesting the remote node initiate the copying (1720—NO),the process proceeds to Step 1724.

In Step 1722, the local space manager requests and receives the layoutof the requested data from the remote space manager. More details of theprocess of Step 1722 are discussed in relation to FIG. 18A. After Step1722, the process proceeds to Step 1706.

In Step 1724, the local space manager requests and receives therequested data from the remote node. More details of the process of Step1724 are discussed in relation to FIG. 18D. After Step 1724, the processproceeds to Step 1712.

FIG. 18A shows a flowchart of a method for requesting and receiving adata layout from a remote space manager, in accordance with one or moreembodiments of the invention. All or a portion of the method shown inFIG. 18A may be performed by local file system container and/or localspace manager thereof. While the various steps in this flowchart arepresented and described sequentially, one of ordinary skill in therelevant art will appreciate that some or all of the steps may beexecuted in different orders, may be combined or omitted, and some orall steps may be executed in parallel.

In Step 1800, the space manager determines if the sparse virtual spaceregion (one or more sparse virtual space segments) associated with therequested data is already locally available. In one or more embodimentsof the invention, the local node may already have received and stored acopy of the sparse virtual space segments related to the requested dataand will therefore not need to request the sparse virtual space regionagain, but will instead utilize the existing copy of the sparse virtualspace region. However, in one embodiment of the invention, if the localspace manager is attempting to access the requested data for the firsttime, a copy of the sparse virtual space segments associated with therequested data will not be present on the local node, and thereforeneeds to be requested from the remote node that manages the requesteddata.

If the sparse virtual space region of the requested data is not locallyavailable and needs to be requested (1800—NO), the process proceeds toStep 1802. Alternatively, if the sparse virtual space region of therequested data is already locally available (1800—YES), the processproceeds to Step 1806.

In Step 1802, the file system container, of the local node, sends arequest to receive a copy of the sparse virtual space region associatedwith the requested data. In one or more embodiments of the invention,the local space manager generates the request based on theidentification of the node that manages the logical volume to which therequested data is associated. Accordingly, in one embodiment of theinvention, the sparse virtual space region request may include the fileidentifier, the file offset, an identification of the logical volume,and specify, as the recipient, the remote node that manages the logicalvolume associated with the file (and therefore associated with therequested data) by using, for example, an IP address of that remotenode.

In one or more embodiments of the invention, the local file systemcontainer sends the sparse virtual space region request to the hardwarelayer of the local node, where, in turn, one or more components of thelocal hardware layer send the sparse virtual space region request to theremote node via a communication interface of the local node and acommunication interface of the remote node.

In Step 1804, the local node (and the local file system container andlocal space manager thereof) receives the sparse virtual space regionassociated with the requested data from the remote node. In oneembodiment of the invention, the sparse virtual space region is receivedvia a communication interface of the local node and is processed by thelocal space manager.

In one or more embodiments of the invention, once the sparse virtualspace region is received by the local node, the local space manager isable to identify the memory pool(s) and/or persistent storage pool(s)associated with the requested data. Specifically, the local spacemanager is able to identify the individual memory pool segments and/orpersistent storage pool segments associated with the sparse virtualspace segments for the requested data. However, as the local spacemanager does not have access to a copy of those pools (or segmentsthereof), the space manager needs to request the associations providedby the pool segments from the remote node (as explained in Step 1806).

In Step 1806, the file system container, of the local node, sends arequest to receive a copy of the data layout (the physical location ofthe requested data) to the remote node. In one or more embodiments ofthe invention, the space manager generates the data layout request basedon the memory and/or persistent storage pool segments associated withthe sparse virtual space segments of the requested data.

Accordingly, in one embodiment of the invention, the data layout requestmay include a reference to the specific memory and/or persistent storagepool segments associated with the requested data, such that remote spacemanager can quickly identify the physical location associated with thosepool segments and send the physical location address(es) back to thelocal node.

In one or more embodiments of the invention, although the local nodemaintains a copy of the sparse virtual space region associated with therequested data, the local space manager is unable to identify thephysical location of the requested data, as the local file systemmanager lacks the associations between the sparse virtual space regionand the physical location(s) of the requested data (e.g., via the poolsassociated in between). Accordingly, although the local space managermay be able to identify the specific memory and/or persistent storagepool segments associated with the requested data, the local spacemanager cannot identify the exact physical addresses at which that datais located, without first receiving a data layout (the memory and/orpersistent storage pool associations to the underlying physicallocations of the data).

In one or more embodiments of the invention, the local file systemcontainer sends the data layout request to the hardware layer of thelocal node, where, in turn, one or more components of the local hardwarelayer send the data layout request to the remote node via acommunication interface of the local node and a communication interfaceof the remote node.

In Step 1808, the local node (and the local file system container andlocal space manager thereof) receives the data layout for the requesteddata. In one or more embodiments of the invention, the data layoutincludes the memory and/or persistent storage pool associations to theunderlying physical locations of the data. Accordingly, in one or moreembodiments of the invention, the local space manager then identifiesthe exact physical locations of the requested data is (e.g., the memoryand/or persistent storage segments and their associated addresses).

FIG. 18B shows a flowchart of a method for servicing a sparse virtualspace region request, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 18B may beperformed by remote node and/or remote space manager thereof. While thevarious steps in this flowchart are presented and describedsequentially, one of ordinary skill in the relevant art will appreciatethat some or all of the steps may be executed in different orders, maybe combined or omitted, and some or all steps may be executed inparallel.

In Step 1810, the remote node receives a sparse virtual space regionrequest from the local node (see e.g., FIG. 18A). In one or moreembodiments of the invention, the sparse virtual space region requestincludes the file identifier, the file offset, and an identification ofthe logical volume associated with the requested data. In one embodimentof the invention, the sparse virtual space region request is receivedvia a communication interface of the remote node that operativelyconnects the remote node and the local node.

In Step 1812, the space manager of the remote node fetches the sparsevirtual space region requested by the local node. In one embodiment ofthe invention, where the sparse virtual space region request includesthe file identifier and file offset specific to the requested data, theremote space manager uses the file identifier to identify a logicalvolume and a logical volume offset, within that logical volume,associated with file identifier. Once the logical volume offset isknown, the sparse virtual space segment(s) associated with that file aresimilarly identified (e.g., the sparse virtual space region).

Alternatively, in one or more embodiments of the invention, the sparsevirtual space region request may specify the logical volume (alreadyidentified by the local node), for which the remote node then uses thefile identifier to locate the logical volume offset, within that logicalvolume identified in the request. Similarly, once the logical volumeoffset is known, the sparse virtual space segment(s) associated withthat file are identified (e.g., the sparse virtual space region).

In Step 1814, the remote node sends a copy of the sparse virtual spaceregion associated with the sparse virtual space region request to thelocal node. In one or more embodiments of the invention, the remotespace manager generates a command to copy the identified sparse virtualspace region to the local node. The sparse virtual space region is thensent to the local node via a communication interface of the remote nodeand local node, respectively.

FIG. 18C shows a flowchart of a method for servicing a data layoutrequest, in accordance with one or more embodiments of the invention.All or a portion of the method shown in FIG. 18C may be performed byremote node and/or remote space manager thereof. While the various stepsin this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In Step 1816, the remote node receives a data layout request from thelocal node (see e.g., FIG. 18A). In one or more embodiments of theinvention, the data layout request may include a reference to thespecific memory and/or persistent storage pool segments associated withthe requested data. In one embodiment of the invention, the data layoutrequest is received via a communication interface of the remote nodethat operatively connects the remote node and the local node.

In Step 1818, the space manager of the remote node fetches the datalayout requested by the local node. In one embodiment of the invention,the data layout specifies a reference to the specific memory and/orpersistent storage pool segments associated with the requested data.

In one or more embodiments of the invention, as the memory and/orpersistent storage pool segments have already been identified (by thelocal node) in the data layout request, the remote space manager doesnot have to locate the sparse virtual space segments associated with therequested data. Rather, by using the already-identified memory and/orpersistent storage pool segments, the remote space manager may readilyidentifies the physical locations in the underlying hardware (e.g., thephysical address(es) on one or more memory and/or persistent storagedevices) associated with each pool segment.

In Step 1820, the remote node sends a copy of the data layoutcorresponding to the data layout request to the local node. In one ormore embodiments of the invention, the remote space manager generates acommand to copy the data layout to the local node. In turn, the datalayout is then sent to the local node via a communication interface ofthe remote node and local node, respectively.

FIG. 18D shows a flowchart of a method for requesting and receiving datafrom a remote node, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 18D may beperformed by local file system container and/or local space managerthereof. While the various steps in this flowchart are presented anddescribed sequentially, one of ordinary skill in the relevant art willappreciate that some or all of the steps may be executed in differentorders, may be combined or omitted, and some or all steps may beexecuted in parallel.

In Step 1822, the file system container, of the local node, sends arequest to receive a copy of the requested data to the remote node. Inone or more embodiments of the invention, the local space managergenerates the request based on the identification of the node thatmanages the logical volume to which the file is associated. Accordingly,in one embodiment of the invention, the copy request may include thefile identifier, the file offset, an identification of the logicalvolume, and specify, as the recipient, the remote node that manages thelogical volume associated with the file (and therefore associated withthe requested data) by using, for example, an IP address of that remotenode.

In one or more embodiments of the invention, the local file systemcontainer sends the copy request to the hardware layer of the localnode, where, in turn, one or more components of the local hardware layersend the copy request to the remote node via a communication interfaceof the local node and a communication interface of the remote node,respectively.

In Step 1824, the local node (and the local file system container andlocal space manager thereof) receives a copy of the requested data (asspecified in the original mapping request issued by the application). Inone embodiment of the invention, the requested data is received via acommunication interface of the local node and is processed by the localspace manager.

In one or more embodiments of the invention, once the requested data isreceived by the local node, the local space is able to identify thephysical location of the data within one or more memory device(s) of thelocal node. Accordingly, as the physical location is known, the localspace manager is then able to generate a virtual-to-physical addressmapping based on the virtual address specified in the mapping request,and the physical address of the local copy of the requested data.

FIG. 18E shows a flowchart of a method for servicing request for data tobe transmitted to a local node, from a remote node. All or a portion ofthe method shown in FIG. 18E may be performed by a remote file systemcontainer and/or space manager thereof. While the various steps in thisflowchart are presented and described sequentially, one of ordinaryskill in the relevant art will appreciate that some or all of the stepsmay be executed in different orders, may be combined or omitted, andsome or all steps may be executed in parallel.

In Step 1826, the file system container, of the remote node, receives arequest to copy data located in the remote node to a local node (seee.g., FIG. 18D). As discussed above in Step 1822, in one or moreembodiments of the invention, the request for data may include the fileidentifier, the file offset, and an identification of the logical volumeassociated with the requested data. In one or more embodiments of theinvention, the space manager of the remote file system containerprocesses the copy request.

In Step 1828, the space manager (of the remote node) identifies one ormore sparse virtual space segments associated with the requested data.In one or more embodiments of the invention, as discussed in Step 700above, the mapping request may specify the data using a file identifierand a file offset.

In one or more embodiments of the invention, the space manager (of theremote node) uses the file identifier to identify a logical volume and alogical volume offset, within that logical volume, associated with fileidentifier. Once the logical volume offset is known, the sparse virtualspace segment(s) associated with that file are similarly identified.Further, using the specified file offset, one or more sparse virtualspace segments are identified (e.g., located) that are specific to thedata specified in the mapping request. Accordingly, at this point, thespace manager (of the remote node) has located, in the sparse virtualspace, the data specified in the mapping request.

In Step 1830, the space manager (of the remote node) identifies thepools mapped to the one or more sparse virtual space segments identifiedin Step 1828. In one or more embodiments of the invention, the method ofStep 1830 is substantially similar to the method disclosed in Step 716.Accordingly, in one embodiment of the invention, similarly disclosedprocesses of Step 1830 have all of the same properties and purpose asdescribed in Step 716.

In Step 1832, the space manager (of the remote note) identifies thephysical location of the data in storage. As discussed in thedescription of in FIG. 4 and Step 720, each identified persistentstorage pool segment is associated with persistent storage segments thatidentify the physical locations of the requested data. Further, eachidentified memory pool segment is associated with memory segments thatidentify the physical locations of the requested data. In one or moreembodiments of the invention, the storage device type of the requesteddata is not relevant as the requested data will need to be copied tolocal memory of the local node (as the requested data is not located onthe local node).

In Step 1834, the space manager (of the remote node) generates a commandto copy the data from the identified physical address(es) in the remotenode to the local node. In one or more embodiments of the invention, thespace manager identifies the local node based on the copy requestreceived in Step 1826.

FIG. 19A shows a flowchart of a method for syncing data changes of amemory mapped region where the data was copied from its physicallocation on a remote node, in accordance with one or more embodiments ofthe invention. All or a portion of the method shown in FIG. 19A may beperformed by one or more components of the node. While the various stepsin this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In one or more embodiments of the invention, the method of FIG. 19A issubstantially similar to the method disclosed in FIG. 9A. Accordingly,in one embodiment of the invention, similarly disclosed steps in FIG.19A have all of the same properties and purpose as described above inFIG. 19A. Accordingly, only differing and/or additional properties andprocesses are described below.

After the competition of Step 1904 (similar to Step 904, where thekernel module of the OS intercepts and forwards the sync command to thefile system container of the node), the process proceeds to Step 1906.Like Step 906 of FIG. 9A, in Step 1906 of FIG. 19A, the file systemcontainer, having received and processed the sync command forwarded bythe kernel module, re-initiates the sync process by forwarding one ormore sync commands back to the OS.

However, unlike Step 906 of FIG. 19A, in Step 1906 of FIG. 19A, the filesystem container may also generate a command to write data to remotememory, from which the local copy of the modified data originallyemanated. More details of the process of Step 1906 are discussed inrelation to FIG. 19B below.

FIG. 19B shows a flowchart of a method for servicing a sync command, inaccordance with one or more embodiments of the invention. All or aportion of the method shown in FIG. 19B may be performed by the filesystem container and/or the space manager thereof. While the varioussteps in this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In Step 1910, the file system container receives a sync command for datathat was being directly manipulated by the application. In one or moreembodiments of the invention, the method of Step 1910 is substantiallysimilar to the method discussed in description of Step 910. Accordingly,in one embodiment of the invention, similarly disclosed processes ofStep 1910 have all of the same properties and purpose as described forStep 910.

In Step 1912, the file system container forwards the sync command to theOS in order to commit the data, located in cache, to memory. In one ormore embodiments of the invention, the method of Step 1912 issubstantially similar to the method discussed in description of Step912. Accordingly, in one embodiment of the invention, similarlydisclosed processes of Step 1912 have all of the same properties andpurpose as described for Step 912.

In Step 1914, the file system container generates a command to copy thedata, synced in Step 1912, to the remote note. In one or moreembodiments of the invention, the data manipulated by the application,executing on the local node, is normally located on a physical device ofa remote node (from where it was copied). Accordingly, in one embodimentof the invention, committed changes (e.g., those resulting from a synccommand of the application) are copied to the physical location of thedata on the remote node.

In one or more embodiments of the invention, the space manager generatesa command that instructs the one or more hardware layer components ofthe local node to copy the data from the local physical location (wherethe local application is manipulating the data) to the physical locationon the remote node, from where the data was originally located.

In Step 1916, the file system container transmits the command (to copydata from local memory to the remote node) to the OS of the local node.In one or more embodiments of the invention, the file system containeris further configured to await confirmation that the remote node hasreceived and stored the modified data.

In Step 1918, the file system container receives confirmation, from theOS, that the data (associated with the sync command) was successfullycopied to the remote node.

In one embodiment of the invention, if the file system container doesnot receive an indication that data was successfully copied to theremote node, Step 1914 and Step 1916 may be repeated. In one or moreembodiments of the invention, if the file system container continues tofail to receive confirmation that the remote node successfully receivedthe data, the file system container inform the application that the syncoperation has failed and prevent further manipulation of the data.Alternatively, in one embodiment of the invention, the file systemcontainer (and/or the space manager thereof) may identify anotherlocation to store the manipulated data, until the manipulated data maybe properly copied back to the remote node.

FIG. 19C shows a flowchart of a method for servicing a write request, inaccordance with one or more embodiments of the invention. All or aportion of the method shown in FIG. 19C may be performed by the hardwarelayer of a remote node and/or the components thereof. While the varioussteps in this flowchart are presented and described sequentially, one ofordinary skill in the relevant art will appreciate that some or all ofthe steps may be executed in different orders, may be combined oromitted, and some or all steps may be executed in parallel.

In Step 1920, a remote node receives data from a local node. In one ormore embodiments of the invention, as discussed in the description ofStep 1914, the copy request, received from local node, specifies thephysical address (and associated device) on which to copy the data. Inone or more embodiments of the invention, the copy request is receivedvia a communication interface of the remote node.

In Step 1922, the remote node writes the data of the copy request tophysical location specified in the copy request. In one or moreembodiments of the invention, after receiving the copy request fromcommunication interface, a processor of the remote node processes thecopy request by locating the physical device (specified by the copyrequest) and copying that data to the physical location (as specified bythe copy request).

In Step 1924, the remote node generates and transmits a confirmation, tothe local node, that the data specified in the copy request wassuccessfully copied to the local memory device and/or persistent storagedevice. In one or more embodiments of the invention, the confirmation istransmitted to the local node via a communication interface of theremote node.

FIG. 20 shows an example in accordance with one or more embodiments ofthe invention. The following use case is for explanatory purposes onlyand not intended to limit the scope to this embodiment.

In FIG. 20, consider a scenario in which, at (1), application (2012)issues a mapping request for data in virtual address space (2020) toestablish direct access to memory (2038). The mapping request specifiesa virtual address of the virtual address space (2020) and specific datausing a file identifier and a file offset.

At (2), application container (2002) forwards the mapping request to theOS (2008). Here, the application container (2002) forwards the request,unaltered to the OS (2008) of the node (2000). Further, the OS (2008)passes the mapping request to hardware layer (2010) of the node (2000)without any additional processing.

At (3), the processor (2034) receives the mapping request in thehardware layer (2010) and forwards the request to the MMU (not shown).The MMU (not shown) performs a lookup in TLB (not shown) to locate aphysical address associated with the virtual address of the mappingrequest. However, the TLB (not shown) does not contain avirtual-to-physical address mapping for the specified virtual address.Accordingly, the MMU (not shown) issues a page fault to the OS (2008)that includes the mapping request.

At (4), the kernel module (2030) detects a page fault in the OS (2008)and interrupts normal handling of the page fault by the OS (2008).Specifically, the kernel module (2030) intercepts the page fault andforwards the mapping request (of the page fault) to the file systemcontainer (2006).

At (5), the space manager (2028) of the file system container (2006)receives the mapping request and locates the file in the sparse virtualspace by analyzing the file identifier to identify a logical volumeassociated with file identifier. However, at (5), the space manager(2028) identifies that the logical volume associated with the fileidentifier is not managed by the local node (2000). The space manager(2028), knowing the requested data needs to be copied to local memory(2038), from a remote node, identifies a sufficient region (e.g.,physical addresses) of local memory (2038) on which to copy therequested data.

Accordingly, the space manager (2028) identifies the node that managesthe identified logical volume as remote node (2042). Accordingly, spacemanager (2028) generates a request to receive a copy of the requesteddata from the remote node (2042). The copy request includes the fileidentifier, the file offset, an identification of the logical volume,the location (on local memory (2038) for where to copy the data to, andspecifies, as the recipient, the remote node that manages the logicalvolume associated with the file (and therefore associated with therequested data) by using a known IP address of that remote node (2042).

At (6), the file system container (2006) sends the copy request to thehardware layer (2010) of the local node (2000). One or more componentsof the hardware layer (2010) then processes and the request andgenerates a new copy request suitable for the operative connectionbetween local node (2000) and remote node (2042). The request is thensent to the communication interface (2032) that operatively connects thenodes (2000, 2042)

At (7), the local node (2000) sends the copy request to the remote node(2042) via communication interface (2032) of hardware layer (2010).

At (8), the copy request is received by the remote node (2042) andprocessed in the hardware layer (2048). The copy request is then sent tothe OS (2046) for additional processing.

At (9), the kernel module (2052) of OS (2046) identifies the copyrequest and interrupts the normal processing of the request by the OS(2046). Specifically, the kernel module (2052) intercepts the copyrequest and forwards the copy request to the file system container(2044) of the remote node (2042).

At (10), the space manager (2050) of remote node (2042) receives thecopy request and locates the sparse virtual space segment(s), memoryand/or persistent storage pool(s), and physical location of the dataassociated with the data specified in the copy request.

After identifying the physical location(s) of the data specified in thecopy request, the space manager (2050) generates a command to copy thedata from the identified physical locations on the remote node (2042) tothe local node (2000) from which the copy request originated.

At (11), the file system container (2044) of the remote node (2042)transmits the copy command, generated by the space manager (2050), tothe OS (2046). After the OS (2046) receives the copy command, the OS(2046) interacts with the hardware layer (2048) to ensure servicing ofthe copy request.

At (12), in the hardware layer (2048) of the remote node (2042), thedata specified in the copy request is sent from its location in remotememory (2058) to the communication interface (2054) operativelyconnected to local node (2000). To achieve this, a processor (not shown)of the hardware layer (2048) processes the copy request and generatescommands to copy the requested data from remote memory (2058) via an MMU(not shown) and TLB (not shown) to communication interface (2054).

At (13), the communication interface (2054) of the remote node (2042)receives the copy request from the processor (not shown) and sends thedata, specified in the copy request, to the local node (2000).

At (14), the communication interface (2032) of the local node (2000)receives the data from the remote node (2042). Further, the processor(not shown) of the hardware layer (2010) of local node (2000) processesand copies that data to the physical location of local memory (2038)identified by the space manager (2028) in at step (5).

Additionally, after the data has been copied to local memory (2038), thefile system container (2006) forwards the virtual-to-physical addressmapping to the MMU (not shown). In one or more embodiments of theinvention, the file system container (2006) transmits thevirtual-to-physical address mapping to hardware layer (2010) via the OS(2008). In turn the OS (2008) informs the application container (2002)and the application (2012) that the memory mapping request wassuccessfully serviced, and direct access has been established.

FIG. 21 shows an example in accordance with one or more embodiments ofthe invention. The following use case is for explanatory purposes onlyand not intended to limit the scope to this embodiment.

In FIG. 21, consider a scenario in which, at (1), application (2112)issues a sync command for data being manipulated in the virtual addressspace (2120) via direct access to memory (2138). The sync commandspecifies a virtual address of the virtual address space (2120) and themodified data.

At (2), application container (2102) forwards the sync command to the OS(2108). Here, the application container (2102) forwards the request,unaltered to the OS (2108) of the node (2100). At (3), the kernel module(2130) detects the sync command in the OS (2108) and interrupts normalhandling of the sync command by the OS (2108). Specifically, the kernelmodule (2130) intercepts the sync command and forwards the sync commandto the file system container (2106).

At (4), the space manager (2128) of the file system container (2106)receives the sync command and identifies each memory segment affected bythe sync command. Specifically, space manager (2128) analyzes the synccommand and identifies that the sync command is associated with datathat is located on remote node (2142). Thus, the space manager (2128)generates two sync commands, a first sync command to copy anyuncommitted data (in processor cache, not shown) to local memory (2138)(as identified in the memory pool), and a second sync command to copyany manipulated data to the location in the remote node (2142) where thedata originated (remote memory (2158)).

At (5), the file system container (2106) forwards the sync commands tothe processor (1234) through OS (2108). At (6), processor (not shown)receives the sync commands, identifies all relevant, uncommitted data(in cache, not shown), associated with the sync command, and initiatescopying that data to local memory (2138).

At (7), the communication interface (2132) receives the copy requestfrom the processor (not shown) and sends the data specified in the copyrequest (i.e., the data which is now stored in the local memory (2138))to the remote node (2148) via RDMA.

At (8), the remote node (2142) receives the data specified in the copyrequest via communication interface (2154) and copies that data toremote memory (2158). One or more components of the hardware layer(2148) of remote node (2142) coordinate receiving the data from thecommunication interface (2154) and copying that data to specifiedlocation in remote memory (2158).

FIG. 22 shows a diagram of a cluster (2200) in accordance with one ormore embodiments of the invention. In one embodiment of the invention,cluster (2200) includes a unified namespace manager (2260) with a toplevel file system namespace (2262) and one or more node(s) (e.g., node H(2202), node I (2204), node J (2206)). Similarly named parts shown inFIG. 22 have all of the same properties and functionalities as discussedin the description of FIG. 13. Accordingly, only additional propertiesand functionalities will be described below.

In one or more embodiments of the invention, unified namespace manager(2260) is hardware and/or software configured to manage (e.g., create,update, enforce rules of) a top level file system namespace (e.g., toplevel file system namespace (2262)). In one embodiment of the invention,the unified namespace manager (2260) coordinates with one or more nodes(2202, 2204, 2206) to provide access to and/or provide copies of a toplevel file system namespace (2262) and the contents thereof. Further, inone or more embodiments of the invention, the unified namespace manager(2260) communicates with each node (2202, 2204, 2206) of the cluster(2200) to receive and disperse updates relating to the top level filesystem namespace (2262). In one embodiment of the invention, the unifiednamespace manager (2260) provides centralized management of the toplevel file system namespace (2262) to all devices (e.g., nodes (2202,2204, 2206)) within a cluster (2200).

In one or more embodiments of the invention, the unified namespacemanager (2260) may be executing on hardware independent of other nodeswithin the cluster (2200). Alternatively, a node (2202, 2204, 2206) ofthe cluster (2200) may be performing the functions of the unifiednamespace manager (2260). As discussed in the description of FIG. 13,each node (2202, 2204, 2206) within the cluster (2200) may beoperatively connected to every other node (2202, 2204, 2006). Further,in one or more embodiments of the invention, the hardware, on which theunified namespace manager (2260) is executing, is operatively connectedto one or all of the node(s) (2202, 2204, 2206) of the cluster (2200).

In one or more embodiments of the invention, top level file systemnamespace (2262) is a data construct that includes a comprehensive listof file system metadata (file system name(s), file system identifier(s),file system address(es)). One or more embodiments of a top level filesystem namespace (2262) are discussed in the description of FIG. 23.

While FIG. 22 shows a specific configuration of a unified namespacemanager (e.g., unified namespace manager (2260)), other configurationsmay be used without departing from the scope of this disclosure.Accordingly, embodiments disclosed herein should not be limited to theconfiguration of devices and/or components shown in FIG. 22.

FIG. 23 shows a diagram of top level file system namespace (2362), inaccordance with one or more embodiments of the invention. In one or moreembodiments of the invention, a top level file system namespace (2362)is a data construct that includes metadata related to one or more filesystem(s) (file system entry A (2302), file system entry B (2304), filesystem entry C (2306)). Specifically, in one or more embodiments of theinvention, a top level file system namespace (2362) associates one ormore file system name(s) to one or more file system identifier(s) andone or more file system addresses(s), organized into a logical format(e.g., table, object, record, etc.). Each of these components isdescribed below.

In one or more embodiments of the invention, a file system (not shown)is a construct that organizes data physically located on one or morehardware components of one or more nodes (i.e., memory and/or persistentstorage). A file system may enable the labeling and grouping of data(e.g., files) in a hierarchy (e.g., folders) to provide a virtualstructure of the underlying data to be utilized by one or moreapplication(s) of one or more node(s). In one or more embodiments of theinvention, a file system utilizes one or more protocols to ensure aconsistent standardization and organization of the data (e.g., NewTechnology File System (NTFS), File Allocation Table (FAT), Network FileSystem (NFS), Server Message Block (SMB), etc.).

In one or more embodiments of the invention, a file system entry (e.g.,file system entry A (2302), file system entry B (2304), file systementry C (2306)) is a data construct that includes information necessaryto enable the identification and existence of a file system. In one ormore embodiments of the invention, a file system entry (2302, 2304,2306) is specific to one file system and provides various metadata aboutthat file system including the file system name (2303, 2305, 2307), thefile system identifier (2308, 2310, 2312), and/or the file systemaddress (2314, 2316, 2318).

In one or more embodiments of the invention, a file system name (e.g.,file system name A (2303), file system name B (2305), file system name C(2307)) is an alphanumeric expression associated with a file system. Thealphanumeric expression may be encoded using a standard protocol foralphanumeric characters (e.g., Unicode, American Standard Code forInformation Interchange (ANSII)). In one embodiment of the invention,the file system name (2303, 2305, 2307) is provided by a user of one ormore nodes (not shown) that initiated the creation of the file systemand may further be a string of text that uniquely identifies the filesystem to one or more users (e.g., “file system 1”, “fs4”, “Joe'sFiles”, etc.). Alternatively, in one embodiment of the invention, a filesystem name (2303, 2305, 2307) may be automatically generated by one ormore nodes when the file system is initially created. One of ordinaryskill in the art, having the benefit of this detailed description, wouldappreciate that a file system name may be any alphanumeric expressionthat is unique to the associated file system.

In one or more embodiments of the invention, a file system identifier(e.g., file system identifier A (2308), file system identifier B (2310),file system identifier C (2312)) is a unique identifier of each filesystem within the top level file system namespace (2362). In oneembodiment of the invention, the file system identifier (2308, 2310,2312) is a unique number assigned to the file system that allows foreach device of the cluster (e.g., the unified namespace manager, one ormore node(s)) to reference the file system without using the file systemname (2303, 2305, 2307) associated with the file system. Further, in oneembodiment of the invention, each file system identifier (2308, 2310,2312) may be a number of equal length (e.g., a 5, 10, or 20 digitnumber) that provides uniformity for the for the file system identifiers(2308, 2310, 2312) of the top level file system namespace (2362). One ofordinary skill in the art, having the benefit of this detaileddescription, would appreciate that a file system identifier may be anytext expression and/or numerical value that is unique to the associatedfile system.

In one or more embodiments of the invention, a file system identifier(2308, 2310, 2312) is generated by the unified namespace manager whenthe file system is added to the top level file system namespace (2362).Alternatively, in one or more embodiments of the invention, a filesystem identifier (2308, 2310, 2312) is generated by a node when thefile system is initially created.

In one or more embodiments of the invention, a file system address(e.g., file system address A (2314), file system address B (2316), filesystem address C (2318)) is a unique address associated with the device(e.g., node) that hosts the file system. In one or more embodiments ofthe invention, a file system is hosted on a node in the cluster, whereeach node is assigned a unique address within the cluster. Specifically,as discussed in the description of FIG. 13, each node within a clustermay be assigned a unique identifier (e.g., an IP address) to be usedwhen utilizing one or more protocols of a network that operativelyconnects the nodes.

While FIG. 23 shows a specific configuration of a top level file systemnamespace (e.g., top level file system namespace (2362)), otherconfigurations may be used without departing from the scope of thisdisclosure. Accordingly, embodiments disclosed herein should not belimited to the configuration of devices and/or components shown in FIG.23.

FIG. 24A shows a flowchart of a method of creating a new file system, inaccordance with one or more embodiments of the invention. All or aportion of the method shown in FIG. 24A may be performed by the filesystem container or the space manager thereof. Another component of thesystem may perform this method without departing from the invention.While the various steps in this flowchart are presented and describedsequentially, one of ordinary skill in the relevant art will appreciatethat some or all of the steps may be executed in different orders, maybe combined or omitted, and some or all steps may be executed inparallel.

In Step 2400, the file system container (or the space manager thereof)generates a new file system name and file system identifier for a newfile system. In one or more embodiments of the invention, the spacemanager may initiate the generation of new file system based on acommand (received by the file system container) to create a new filesystem. The command to create the file system may specify otherproperties of the file system, for example, the size to allocate to thefile system, the file system name, and/or the type of storage toutilize. In one or more embodiments of the invention, the node thatinitiates the creation of new file system may be considered the “host”of that file system by other devices (e.g., other nodes, the unifiednamespace manager) of the cluster.

In one or more embodiments of the invention, prior to generating a newfile system name and/or file system identifier, the space manager mayanalyze an existing copy of the top level file system namespace todetermine if the specified file system name is available and/or identifyan available file system identifier. For example, in one or moreembodiments of the invention, a file system name (e.g., “fs1”) mayalready exist in the top level file system namespace and therefore thenew file system may not be assigned that specific name (i.e., an erroris returned requesting a new file system name). Further, as anotherexample, the space manager may query the top level file system namespaceto identify an available file system identifier to assign the new filesystem (thereby ensuring the file system identifier is unique).

In one or more embodiments of the invention, the node does not generatethe file system identifier. Instead, in one embodiment of the invention,the unified namespace manager generates the file system identifier whenreference to the new file system is added to the top level file systemnamespace (see e.g., Step 2410).

In Step 2402, the space manager allocates a region of sparse virtualspace (one or more sparse virtual space segments) to be associated withthe new file system. In one or more embodiments of the invention, thespace manager locates one or more sparse virtual space segment(s) that,in total, correspond to the size specified by the command to create thefile system.

In one or more embodiments of the invention, a space manager mayidentify available sparse virtual space segments by analyzing the sparsevirtual space and locating one or more sparse virtual space segment(s)that are not currently associated with a memory pool or a persistentstorage pool (and are therefore not associated with any data).Alternatively, in one or more embodiments of the invention, the spacemanager may identify available sparse virtual space segments by making aseparate determination regarding the availability indicated by eachsparse virtual space segment, individually.

Further, in one or more embodiments of the invention, although the spacemanager associates the new file system with a sparse virtual spaceregion, the space manager may not associate the sparse virtual spaceregion with a pool (i.e., memory pool and/or persistent storage pool)until data is requested to be written using that file system.Accordingly, in one embodiment of the invention, while a file system maybe allocated to a sparse virtual space region correlating to therequested size, physical storage devices (i.e., memory and/or persistentstorage) may not be associated with the sparse virtual space regionand/or may not be sufficiently available to satisfy the allocated size.

In Step 2404, the space manager associates one or more memory and/orpersistent storage pool(s) to the sparse virtual space region allocatedfor the new file system. In one or more embodiments of the invention,the space manager may create one or more new pool(s) to associate withthe sparse virtual space region and/or identify one or more existingpool(s) (or segments thereof) not already associated with the sparsevirtual space.

In one embodiment of the invention, where data managed by the filesystem must be stored on a particular storage type (memory or persistentstorage), the space manager may create and/or identify pool(s) of thattype (memory or persistent storage) to associate with the sparse virtualspace region. Thus, any physical device mapped to the sparse virtualspace region (associated with the file system) satisfies the specifiedstorage type requirements.

In one or more embodiments of the invention, the association of the ofthe sparse virtual space region to one or more memory and/or persistentstorage pool(s) may not occur until data is requested to be writtenusing the file system. Further, when receiving a write request thatcauses the space manager to associate one or more sparse virtual spacesegments with one or more pool segments, the space manager may associateonly a sufficient number of sparse virtual space segments to satisfy thewrite request. Thus, in one or more embodiments of the invention, thesparse virtual space region associated with the file system may only bepartially associated with one or more pools (correlating to the size ofthe stored data).

Further, in one or more embodiments of the invention, although the spacemanager associates the sparse virtual space region with one or morememory and/or persistent storage pool(s), the space manager may notassociate the memory and/or persistent storage pool(s) with physicalmemory and/or persistent storage devices until data is requested to bewritten using that file system. Accordingly, in one embodiment of theinvention, while a file system may be allocated to a sparse virtualspace region that is associated with one or more memory and/orpersistent storage pool(s), physical storage devices (i.e., memoryand/or persistent storage) may not exist within the node to provide therequested size.

In one or more embodiments of the invention, the association of one ormore pool(s) to the sparse virtual space region (associated with the newfile system) is not necessary for the creation of a new file system.

In Step 2406, the space manager associates one or more regions of memoryand/or persistent storage (e.g., one or more memory and/or persistentstorage segment(s)) with the one or more memory and/or persistentstorage pool(s) associated in Step 2404. In one or more embodiments ofthe invention, the space manager identifies available memory and/orpersistent storage regions and associates the one or more segmentsthereof to the segments of the pools.

In one or more embodiments of the invention, the space manager maylocate one or more available memory and/or persistent storage segment(s)that are already associated with pool segment(s) and re-associate thosememory and/or persistent storage segment(s) with the newly allocatedpool(s) associated with the new file system.

Further, in one embodiment of the invention, each memory and persistentstorage device may have been associated with one or more memory and/orpersistent storage pool(s) when initially added to the cluster. Thus, inone embodiment of the invention, there may not exist any availablememory and/or persistent storage segment(s) to associate with the one ormore newly created memory and/or persistent storage pool(s) untiladditional storage devices are added to one or more node(s) of thecluster.

In one or more embodiments of the invention, the association of one ormore memory and/or persistent storage region(s) to one or more pool(s)(associated with the new file system) is not necessary for the creationof a new file system.

In Step 2408, the file system container informs the unified namespacemanager that a new file system has been created. In one or moreembodiments of the invention, the space manager generates and initiatesthe transmission of a message, to the unified namespace manager, thatincludes the name of the file system, the file system identifier(optional), the unique address of the node, and/or the size allocated tothe file system. The message may be sent to the unified namespacemanager via an operative connection between node and the unifiednamespace manager.

FIG. 24B shows a flowchart of a method of updating a top level filesystem namespace, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 24B may beperformed by the unified namespace manager. Another component of thesystem may perform this method without departing from the invention.While the various steps in this flowchart are presented and describedsequentially, one of ordinary skill in the relevant art will appreciatethat some or all of the steps may be executed in different orders, maybe combined or omitted, and some or all steps may be executed inparallel.

In Step 2410, the unified namespace manager receives a message, from anode, informing that a new file system was created in the cluster. Inone or more embodiments of the invention, the message is received from a“host node” that created and hosts the new file system. As discussed inthe description of Step 2408, the message may include the name of thefile system, the file system identifier (optional), the unique addressof the node, and/or the size allocated to the file system.

In Step 2412, the unified namespace manager updates the top level filesystem namespace to include a new file system entry for the new filesystem. In one or more embodiments of the invention, the unifiednamespace manager adds the file system name, file system identifier, andfile system address (i.e., the unique address of the host node) to thenew file system entry of the top level file system namespace.

In one or more embodiments of the invention, the host node (that createdthe file system) may not have generated a file system identifier for thenew file system when first creating the file system. Accordingly, in oneembodiment of the invention, the unified namespace manager analyzes theexisting file system identifiers, generates a new file system identifierthat is unique to the new file system (i.e., different than anycurrently existing file system identifier), and adds the file systemidentifier to the new file system entry.

Further, in one embodiment of the invention, the host node may not haveincluded the unique address of the node in the message received in Step2412. Thus, in one embodiment of the invention, the unified namespacemanager performs a lookup of the unique address of the node to generateand add the file system address to the new file system entry.Alternatively, in one embodiment of the invention, where the uniqueaddress of the node is the IP address of the host node, the unifiednamespace manager uses the message from the host node (informing of thenew file system) to identify the IP address of the node generate and addthe file system address to the new file system entry.

In Step 2414, the unified namespace manager generates and sends amessage to each node in the cluster informing that the top level filesystem namespace has been updated. In one or more embodiments of theinvention, other devices of the cluster (e.g., other nodes than the hostnode and the unified namespace manager) are unaware of the existence ofthe new file system. Thus, after the top level file system namespace isupdated to include a new file system entry corresponding to the new filesystem, in one or more embodiments of the invention, the unifiednamespace manager generates a message that informs that a new filesystem has been added to the top level file system namespace and sendsthat message to each node in the cluster.

Alternatively, in one or more embodiments of the invention, the unifiednamespace manager generates a message that includes a copy of theupdated top level file system namespace and sends that message to eachnode in the cluster (thereby providing the updated top level file systemnamespace to each node without any additional action of the nodes). Themessage may be sent to each node via an operative connection between thenode(s) and the unified namespace manager.

FIG. 25 shows a flowchart of a method of requesting a top level filesystem namespace, in accordance with one or more embodiments of theinvention. All or a portion of the method shown in FIG. 25 may beperformed by a node, file system container, and/or space managerthereof. Another component of the system may perform this method withoutdeparting from the invention. While the various steps in this flowchartare presented and described sequentially, one of ordinary skill in therelevant art will appreciate that some or all of the steps may beexecuted in different orders, may be combined or omitted, and some orall steps may be executed in parallel.

In Step 2500, a file system container (of a node in the cluster)receives a message from the unified namespace manager informing that thetop level file system namespace has been updated. In one or moreembodiments of the invention, the message from the unified namespacemanager is received via an operative connection between the node andunified namespace manager.

Alternatively, in one or more embodiments of the invention, the messagefrom the unified namespace manager includes the updated top level filesystem namespace (instead of simply informing that the top level filesystem namespace has been updated). In one or more embodiments of theinvention, where the message from the unified namespace manager includesthe updated top level file system namespace, the process proceedsdirectly to Step 2506.

In Step 2502, the file system container sends a request to the unifiednamespace manager for a copy of the updated top level file systemnamespace. In one or more embodiments of the invention, the spacemanager, of the file system container, analyzes the message from theunified namespace manager that the top level file system namespace hasbeen updated, generates a request to receive a copy of the updated toplevel file system namespace, and initiates transmission of that requestvia the file system container.

In one or more embodiments of the invention, the request for the updatedtop level file system namespace includes the unique identifier of thenode (of the node from which the request is being sent) and/or a uniqueaddress associated with the protocol being used to communicate therequest (e.g., an IP address).

In Step 2504, the file system container receives a copy of the updatedtop level file system namespace from the unified namespace manager. Inone or more embodiments of the invention, the updated top level filesystem namespace is sent by the unified namespace manager in response toreceiving the request sent in Step 2502. The file system container thenprovides the copy of the updated top level file system namespace to thespace manager for processing.

In Step 2506, the space manager updates the local copy of the top levelfile system namespace. In one or more embodiments of the invention, thespace manager replaces (e.g., overwrites) the existing copy of the toplevel file system namespace with the updated version. Alternatively, inone or more embodiments of the invention, the space manager may comparethe existing copy of the top level file system namespace with theupdated top level file system namespace to identify one or moredifferences in the top level file system namespace. Additionally, in oneor more embodiments of the invention, the space manager may inform theOS of the updated top level file system namespace and command the OS toupdate any listing of available file systems maintained by the OS.

FIG. 26 shows a flowchart of a method of mounting a file system, inaccordance with one or more embodiments of the invention. All or aportion of the method shown in FIG. 26 may be performed by one or morecomponents of a node. Another component of the system may perform thismethod without departing from the invention. While the various steps inthis flowchart are presented and described sequentially, one of ordinaryskill in the relevant art will appreciate that some or all of the stepsmay be executed in different orders, may be combined or omitted, andsome or all steps may be executed in parallel.

In Step 2600, an application, executing on a node, generates andinitiates the transmission of a request to retrieve a list of availablefile systems. In one or more embodiments of the invention, anapplication is not provided a list of available file systems untilrequested, and therefore must first retrieve information relating to theavailable file systems prior to mounting one or more file systems.

In Step 2602, the kernel module, residing in the OS, intercepts therequest to retrieve the file system listing and forwards the request tothe file system container. In one or more embodiments of the invention,the kernel module is configured identify requests related to filesystems and interrupt normal handling of the requests by the OS.Specifically, the kernel module may redirect requests related to filesystems to the file system container.

In Step 2604, the file system container (and the space manager thereof)receives the request to retrieve a list of available file systems andsends the top level file system namespace to the application (via theOS). In one or more embodiments of the invention, the space manager isconfigured to identify requests for file system listings, generate amessage that includes the top level file system namespace, and initiatetransmission of the message to the requesting entity (e.g., one or moreapplications, the OS, etc.).

In one or more embodiments of the invention, where the file systemcontainer is aware of a top level file system namespace update (e.g., asreceived in Step 2500) but has not yet requested and/or received a copyof the updated top level file system namespace (e.g., as requested andreceived in Steps 2502 and 2504), the space manager may initiate theprocess described in Steps 2502 and 2504, prior to generating themessage that includes an (outdated) top level file system namespace, sothat the updated top level file system namespace can be provided to theapplication. Alternatively, in one embodiment of the invention, thespace manager provides the outdated top level file system namespace tothe application, even though the space manager received a messageinforming of the existence of an updated top level file system namespace(that of Step 2500).

In one or more embodiments of the invention, the space manager mayinject permissions metadata into the top level file system namespacewhen generating the message. In one embodiment of the invention, a spacemanager may be configured to identify the permissions (e.g., privileges,access level, restrictions) of the application requesting the filesystem listing and add that permissions information, for each filesystem, to the file system entries of the top level file systemnamespace.

In Step 2606, the application receives the top level file systemnamespace from OS. In one or more embodiments of the invention, the toplevel file system namespace includes an updated listing of all filesystems accessible within the cluster and may further include permissioninformation specific to each file system.

In Step 2608, the application identifies one or more file system(s)listed in the top level file system namespace. In one or moreembodiments of the invention, the identification of one or more filesystem(s) is based on a requirement of a larger process executing by theapplication, for which the application must access certain data (e.g.,files, file segment(s), etc.) managed by identified file system.Alternatively, in one or more embodiments of the invention, theapplication may identify all available file systems within the top levelfile system namespace to be mounted.

In Step 2610, the application mounts one or more file system(s)identified in Step 2608. In one or more embodiments of the invention,the application generates and sends a command to mount the file systemthat specifies the file system identifier and file system address.Further, in one embodiment of the invention, the application specifies aregion of the virtual address space to associate with the mounted filesystem.

In one or more embodiments of the invention, the application requests tomount a file system that is managed by a remote node. Thus, in oneembodiment of the invention, when any future requests are made to accessdata of that file system (managed by a remote node), the local spacemanager makes the determination of Step 1702 (1702—NO) and retrieves andaccesses the data as described in FIG. 18A and/or FIG. 18D. Further, inone or more embodiments of the invention, the determination of Step 1702may be based on the file system address associated with the file systemthat manages the requested data (i.e., the file system address not beingthat of the local node).

In one or more embodiments of the invention, the application requests tomount a file system that is managed by the node on which the applicationis executing (e.g., the local node). Thus, in one embodiment of theinvention, when any future requests are made to access data of that filesystem (managed by a local node), the local space manager makes thedetermination of Step 1702 (1702—YES) and retrieves and accesses thedata as described in Steps 1704-1714. Further, in one or moreembodiments of the invention, the determination of Step 1702 may bebased on the address associated with the file system that manages therequested data. Specifically, in one embodiment of the invention, wherethe address associated with the file system is the unique identifier ofthe local node (i.e., the IP address), the space manager is configuredto recognize that the file system address of the of the associated filesystem matches the unique identifier of the node, and thereforedetermine that the file system is locally managed.

Alternatively, at Steps 2602 and 2604, the OS provides the top levelfile system namespace to the application without interception by thekernel module. In one or more embodiments of the invention, the OSmaintains its own copy of the top level file system namespace (asprovided by the space manager), and therefore, instead of the kernelmodule intercepting the request to retrieve the file system listing(sent in Step 2600), the OS responds to the application's request byproviding the top level file system namespace directly to theapplication (as discussed in the description of Step 2606) withoutinvolving the space manager.

FIG. 27 shows an example, in accordance with one or more embodiments ofthe invention. The following use case is for explanatory purposes onlyand not intended to limit the scope to this embodiment.

In FIG. 27, consider a scenario in which, at (1), a space manager (2750)of a remote node (2742) initiates the creation of a new file system. Theinitiation of the creation of the file system may include determining(or executing inputs) that specify a file system name and file systemsize. At (2), the space manager allocates a region of the sparse virtualspace (2751) to create a file system allocation (2770) consistent withthe file system size. After the space manager (2750) allocates the filesystem allocation (2770), the space manager (2750) generates a message,to the unified namespace manager (2760), informing that a new filesystem has been created and includes, at least, the file system name.

At (3), the file system container (2744) initiates the transmission ofthe message to the unified namespace manager (2760) by instructing oneor more components of the hardware layer (2748) to send the message. At(4), the message informing of the new file system (as generated by thespace manager (2750)) is sent to the unified namespace manager (2760)via communication interface (2754) and an operative connection betweenthe remote node (2742) and the unified namespace manager (2760).

At (5), the unified namespace manager (2760) updates the top level filesystem namespace (2762) to include a new entry associated with the newfile system. The unified namespace manager, having not received a filesystem identifier in the message from the remote node (2742), generatesa unique file system identifier for the new file system by analyzingeach existing file system identifier (to avoid more than one use of thesame file system identifier).

Further, having not received a file system address in the message fromthe remote node (2742), the unified namespace manager (2760) identifiesthe IP address of the remote node (2742) from the message informing theunified namespace manager (2760) of the new file system. The unifiednamespace manager (2760) then generates the file system address usingthe IP of the remote node (2742).

At (6), the unified namespace manager (2760) generates and sends amessage to local node (2700) informing the local node (2700) and/or oneor more components thereof, that the top level file system namespace(2762) has been updated.

At (7), having received the message from the unified namespace manager(2760) that the top level file system namespace has been updated, thespace manager (2728) generates and initiates a request to retrieve acopy of the updated top level file system namespace (2762) from theunified namespace manager (2760). In turn, the file system container(2706) initiates transmission of the request by instructing one or morecomponents of the hardware layer (2710) to send the request to theunified namespace manager (2760). At (8), the communication interface(2732) sends the request to the unified namespace manager (2760) via anoperative connection between the local node (2700) and the unifiednamespace manager (2760).

At (9), the unified namespace manager (2760) generates and initiates thetransmission of a message that includes a copy of the updated top levelfile system namespace (2762). At (10), having received the updated toplevel file system namespace (2762), the space manager (2728) overwritesany existing (outdated) copy of the top level file system namespace (notshown) residing in one or more components of the local node (2700).

FIG. 28 shows an example, in accordance with one or more embodiments ofthe invention. The following use case is for explanatory purposes onlyand not intended to limit the scope to this embodiment.

In FIG. 28, consider a scenario in which, at (1), application (2812)issues a mapping request for data in virtual address space (2820) toestablish direct access to data. The mapping request specifies a virtualaddress of the virtual address space (2820) and specific data using afile identifier and a file offset. In this scenario, the file system inwhich the data is located has been mounted, e.g., per FIG. 26, prior to(1).

At (2), application container (2802) forwards the mapping request to theOS (2808) where, the OS (2808) passes the mapping request to hardwarelayer (2810) of the node (2800) without any additional processing. At(3), one or more components of the hardware layer (2810) determine thata virtual-to-physical address mapping for the specified virtual addressdoes not exist. Accordingly, a page fault is issued to the OS (2808)that includes, at least, the mapping request. At (4), the kernel module(2830) detects a page fault in the OS (2808), intercepts the page fault,and forwards the mapping request (of the page fault) to the file systemcontainer (2806).

At (5), the space manager (2828) of the file system container (2806)receives the mapping request and determines that the file systemassociated with data is not managed by the local node (2800).Accordingly, the space manager (2828) identifies the node that managesthe identified file system as remote node (2842). Accordingly, spacemanager (2828) generates a request to receive a copy of the data layoutfrom the remote node (2842). The data layout request includes the fileidentifier, the file offset, the file system identifier and specifies,as the recipient, the remote node that manages the file system by usingfile system address (i.e., the IP address of remote node (2842). At (6),the file system container (2806) initiates the transmission of therequest to the remote node (2842) by instructing one or more componentsof the hardware layer (2810) to send the request. At (7), communicationinterface (2832) sends a request to remote node (2842) via an operativeconnection between the local node (2800) and the remote node (2842).

At (8), one or more components of the hardware layer (2848) of theremote node (2842) receives, processes, and forwards the request to theOS (2846). At (9), the kernel module of remote node (2842) interceptsthe data layout request and forwards the request to the file systemcontainer (2844) and space manager (2850) therein.

At (10), the space manager (2850) locates the sparse virtual spaceregion associated with data specified in the data layout request,generates a message that includes the data layout, and initiatestransmission of the data layout to the local node (2800). At (11), thefile system container (2844) of the remote node (2842) initiates thetransmission of the data layout message to the local node (2800) byinstructing one or more components of the hardware layer (2848) to sendthe data layout message. At (12), communication interface (2854) sendsthe data layout message to local node (2800) via an operative connectionbetween the local node (2800) and the remote node (2842).

At (13), after receiving the data layout from the remote node (2842),the space manager (2828) identifies the physical location(s) that storesthe requested data. Further, although the data requested by application(2812) is associated with a file system that is managed by remote node(2842), the data is not physically located on remote node (2842) (e.g.,in remote memory (2858)). Rather, using the data layout received fromremote node (2842), the space manager (2828) determines that the dataspecified in the mapping request is located in local memory (2838).Accordingly, space manager (2850) generates one or morevirtual-to-physical address mapping(s) that specify one or more virtualaddress(es) of the mapping request and the physical address(es)identified from the data layout.

The file system container (2806) then forwards the virtual-to-physicaladdress mapping(s) to the MMU (not shown). In turn the OS (2808) informsthe application container (2802) and the application (2812) that thememory mapping request was successfully serviced, and direct access hasbeen established. At (14), application (2812) begins to directlymanipulate the data associated with mapping request (from (1)) in localmemory (2838) (albeit through a processor (not shown) storingmanipulated data in cache (not shown) as an intermediary).

One or more embodiments of the invention make it possible to access oneor more file systems managed by one or more nodes of a cluster. Further,the use of a top level file system namespace across the cluster providesa structure through which each node may seamlessly access memory and/orpersistent storage, of one or more nodes, using the file systemsspecified in the top level file system namespace. Accordingly,applications, accessing the data of persistent storage and memory, arenot aware of the actual physical locations of the data being accessedand manipulated. Further, the file system container is configured tohandle memory mapping requests for data in persistent storage. Thus,regardless of the physical location of the data, the file systemcontainer is able to service memory mapping requests and provide directaccess to data by shifting the data, located in persistent storage, tomemory without any additional action on behalf of the application.

Further, embodiments of the invention enable different file systemprotocols (e.g., server message block (SMB), Portable Operating SystemInterface (POSIX), Network File System, etc.) to access the underlyingstorage via a common access point—i.e., the top-level file systemnamespace. Further, because the different file system protocols (or filesystems implementing the different file system protocols) access thefile system using the common access point, there is a commonpresentation of the top-level file system namespace for all of thedifferent file system protocols (or file systems implementing thedifferent file system protocols). Said another way, regardless of whichfile system protocol (or file system implementing file system protocol)is accessing the top-level file system node, they will all be presentedwith the same view of the top-level file system namespace.

While one or more embodiments have been described herein with respect toa limited number of embodiments and examples, those skilled in the art,having benefit of this disclosure, would appreciate that otherembodiments can be devised which do not depart from the scope of theembodiments disclosed herein. Accordingly, the scope should be limitedonly by the attached claims.

What is claimed is:
 1. A method for managing file systems, comprising:receiving, by a unified namespace manager, a first message thatindicates a new file system has been created on a first node; performingan update on a top level file system namespace to include a reference tothe new file system to generate an updated top level file systemnamespace, wherein performing the update on the top level file systemnamespace comprises: generating a file system entry associated with thenew file system, wherein generating the file system entry associatedwith the new file system comprises: obtaining, from the first message, afile system name; obtaining a file system identifier; obtaining a filesystem address; and generating a file system entry comprising the filesystem name, the file system identifier, and the file system address;and adding, to the top level file system namespace, the file systementry; generating, based on the update, a second message that indicatesthe top level file system namespace has been updated; and sending, to asecond node, the second message.
 2. The method of claim 1, wherein thesecond message comprises a copy the updated top level file systemnamespace.
 3. The method of claim 1, wherein the method furthercomprises: receiving, from the second node, a request to send a copy ofthe top level file system namespace; generating, based on the request, athird message that comprises the copy of the updated top level filesystem namespace; and sending, to the second node, the third message. 4.The method of claim 1, wherein obtaining the file system identifiercomprises: identifying, in the top level file system namespace, aplurality of file system identifiers; and generating the file systemidentifier, wherein the file system identifier is different than each ofthe plurality of file system identifiers.
 5. The method of claim 1,wherein obtaining the file system address comprises: identifying, basedon the first message, a unique address of the first node; andgenerating, based on unique address of the first node, the file systemaddress.
 6. A non-transitory computer readable medium comprisinginstructions which, when executed by a computer processor, enables thecomputer processor to perform a method for managing file systems, themethod comprising: receiving, by a unified namespace manager, a firstmessage that indicates a new file system has been created on a firstnode; performing an update on a top level file system namespace toinclude a reference to the new file system to generate an updated toplevel file system namespace, wherein performing the update on the toplevel file system namespace comprises: generating a file system entryassociated with the new file system, wherein generating the file systementry associated with the new file system comprises: obtaining, from thefirst message, a file system name; obtaining a file system identifier;obtaining a file system address; and generating a file system entrycomprising the file system name, the file system identifier, and thefile system address; and adding, to the top level file system namespace,the file system entry; generating, based on the update, a second messagethat indicates the top level file system namespace has been updated; andsending, to a second node, the second message.
 7. The non-transitorycomputer readable medium of claim 6, wherein the second messagecomprises a copy the updated top level file system namespace.
 8. Thenon-transitory computer readable medium of claim 6, wherein the methodfurther comprises: receiving, from the second node, a request to send acopy of the updated top level file system namespace; generating, basedon the request, a third message that comprises the copy of the top levelfile system namespace; and sending, to the second node, the thirdmessage.
 9. The non-transitory computer readable medium of claim 6,wherein obtaining the file system identifier comprises: identifying, inthe top level file system namespace, a plurality of file systemidentifiers; and generating the file system identifier, wherein the filesystem identifier is different than each of the plurality of file systemidentifiers.
 10. The non-transitory computer readable medium of claim 6,wherein obtaining the file system address comprises: identifying, basedon the first message, a unique address of the first node; andgenerating, based on unique address of the first node, the file systemaddress.
 11. A unified namespace manager, comprising: a processor,wherein the processor is configured to: receive a first message thatindicates a new file system has been created on a first node; perform anupdate on a top level file system namespace to include a reference tothe new file system to generate an updated top level file systemnamespace, wherein performing the update on the top level file systemnamespace comprises: generating a file system entry associated with thenew file system, wherein generating the file system entry associatedwith the new file system comprises: obtaining, from the first message, afile system name; obtaining a file system identifier; obtaining a filesystem address; and generating a file system entry comprising the filesystem name, the file system identifier, and the file system address;and adding, to the top level file system namespace, the file systementry; generate, based on the update, a second message that indicatesthe top level file system namespace has been updated; and send, to asecond node, the second message.
 12. The unified namespace manager ofclaim 11, wherein the second message comprises a copy the updated toplevel file system namespace.
 13. The unified namespace manager of claim11, wherein the processor is further configured to: receive, from thesecond node, a request to send a copy of the top level file systemnamespace; generate, based on the request, a third message thatcomprises the copy of the updated top level file system namespace; andsend, to the second node, the third message.
 14. The unified namespacemanager of claim 11, wherein obtaining the file system identifiercomprises: identifying, in the top level file system namespace, aplurality of file system identifiers; and generating the file systemidentifier, wherein the file system identifier is different than each ofthe plurality of file system identifiers.